ui_cocoa: unify Cocoa + Metal event pump on RAWindow

On 10.5 Leopard (and any macOS make-build that runs the bare binary
from a terminal rather than a .app bundle), the window appeared but
didn't respond to keyboard or mouse.  The menu was unreachable.

ROOT CAUSE: input delivery used two different architectures:

  HAVE_COCOA_METAL: RAWindow : NSWindow with a -sendEvent: override.
  AppKit calls -[NSWindow sendEvent:] unconditionally on every event
  destined for the key window, so the override fires with no setup.

  HAVE_COCOA: RApplication : NSApplication with a -sendEvent: override.
  Only fires if NSApp is actually an RApplication instance, which
  requires either NSApplicationMain() + NSPrincipalClass=RApplication
  in Info.plist, or an explicit [RApplication sharedApplication] call
  before any [NSApplication sharedApplication].

The qb/make build bootstraps via plain [NSApplication sharedApplication]
in main() with no NSApplicationMain / Info.plist lookup, so RApplication
was declared but never instantiated.  -sendEvent: was dead code.  Events
flowed through plain NSApplication, got forwarded to the key window's
responder chain, and died in CocoaView's empty -keyDown: stub (which
exists only to squelch the system beep).  Result: window visible,
utterly unresponsive.

FIX: unify on the Metal architecture.  Make HAVE_COCOA also use
RAWindow : NSWindow with the same -sendEvent: override.  AppKit calls
it automatically - no NSPrincipalClass, no class-registration dance.
The two code paths converge on the same event-dispatch structure.

  ui_cocoa.m:
    - Merge the conditional RAWindow-or-RApplication declaration into
      a single unconditional @interface RAWindow : NSWindow.
    - Bracket all 11 NSEvent dot-syntax sites (event.type -> [event type],
      etc.) - now that sendEvent: compiles on the Cocoa path instead
      of being dead code, every dot-access is a compile error on the
      10.5 SDK / GCC 4.0 (pre-Obj-C-2.0, NSEvent's getters aren't
      declared @property there).  Same class of fix as c49a5258c6,
      d38dcb543f, f4d1390a19.
    - Collapse three #if HAVE_COCOA_METAL / #elif HAVE_COCOA case-label
      splits (NSEventTypeFlagsChanged vs NSFlagsChanged, etc.) into
      single modern-name labels.  cocoa_defines.h already provides the
      modern names as aliases on pre-10.12 SDKs.
    - cocoa_create_main_window(): drop the #ifdef HAVE_COCOA_METAL -
      both paths now allocate RAWindow.

Behavioral impact:

  * HAVE_COCOA_METAL (modern macOS, Xcode/make-bundle builds):
    unchanged.  Same RAWindow, same sendEvent:, same event flow.
  * HAVE_COCOA on modern macOS make-bundle: still works - now via
    RAWindow instead of going through the NSPrincipalClass dance.
  * HAVE_COCOA bare-binary from terminal (Leopard PPC, and any make
    build run without .app bundling): NOW WORKS.  Previously unable
    to receive input at all.
  * HAVE_COCOA Xcode builds (RetroArch.xcodeproj, RetroArch_OSX107.
    xcodeproj, RetroArch_PPC.xcodeproj): still work.  Those set
    NSPrincipalClass=RApplication in pkg/apple/OSX/Info.plist, which
    becomes a dangling reference now - but a dangling NSPrincipalClass
    falls back to NSApplication, which is what we want.  The plists
    can be cleaned up in a separate commit.

No per-event overhead change.  NSWindow's sendEvent: dispatch has
the same Obj-C message-send cost as NSApplication's did.  Binary
size grows by a few hundred bytes (the sendEvent: body now compiles
into the non-Metal binary instead of being dead code).

ui/drivers/ui_cocoa.m

@@ -365,17 +365,16 @@ static ui_application_t ui_application_cocoa = {
 
 @end /* @implementation CommandPerformer */
 
-#if defined(HAVE_COCOA_METAL)
+/* RAWindow : NSWindow override.  Both the Metal and non-Metal paths
+ * use this: it's the NSWindow-level sendEvent: hook that AppKit calls
+ * unconditionally for every event destined for this window.  Doing it
+ * here (rather than subclassing NSApplication) means we don't depend
+ * on NSPrincipalClass being set in Info.plist, and the Cocoa / Metal
+ * paths converge on the same event-dispatch architecture. */
 @interface RAWindow : NSWindow
 @end
 
 @implementation RAWindow
-#elif defined(HAVE_COCOA)
-@interface RApplication : NSApplication
-@end
-
-@implementation RApplication
-#endif
 
 #ifdef HAVE_COCOA_METAL
 #define CONVERT_POINT() [apple_platform.renderView convertPoint:[event locationInWindow] fromView:nil]
@@ -395,7 +394,11 @@ static ui_application_t ui_application_cocoa = {
 }
 
 - (void)sendEvent:(NSEvent *)event {
-   NSEventType event_type = event.type;
+   /* Bracket syntax throughout - GCC 4.0 on the pre-Obj-C-2.0 10.5
+    * SDK doesn't accept dot-syntax on NSEvent's plain getter methods
+    * (they aren't declared as @property there).  Modern clang emits
+    * identical code for either form. */
+   NSEventType event_type = [event type];
 
    [super sendEvent:event];
 
@@ -405,12 +408,12 @@ static ui_application_t ui_application_cocoa = {
       case NSEventTypeKeyUp:
          {
             uint32_t i;
-            NSString* ch              = event.characters;
+            NSString* ch              = [event characters];
             uint32_t mod              = 0;
-            const char *inputTextUTF8 = ch.UTF8String;
+            const char *inputTextUTF8 = [ch UTF8String];
             uint32_t character        = inputTextUTF8[0];
-            NSUInteger mods           = event.modifierFlags;
-            uint16_t keycode          = event.keyCode;
+            NSUInteger mods           = [event modifierFlags];
+            uint16_t keycode          = [event keyCode];
 
             if (mods & NSEventModifierFlagCapsLock)
                mod |= RETROKMOD_CAPSLOCK;
@@ -425,7 +428,7 @@ static ui_application_t ui_application_cocoa = {
             if (mods & NSEventModifierFlagNumericPad)
                mod |=  RETROKMOD_NUMLOCK;
 
-            for (i = 1; i < ch.length; i++)
+            for (i = 1; i < [ch length]; i++)
                apple_input_keyboard_event(event_type == NSEventTypeKeyDown,
                      0, inputTextUTF8[i], mod, RETRO_DEVICE_KEYBOARD);
 
@@ -436,16 +439,12 @@ static ui_application_t ui_application_cocoa = {
                      keycode, character, mod, RETRO_DEVICE_KEYBOARD);
          }
          break;
-#if defined(HAVE_COCOA_METAL)
-        case NSEventTypeFlagsChanged:
-#elif defined(HAVE_COCOA)
-        case NSFlagsChanged:
-#endif
+      case NSEventTypeFlagsChanged:
          {
             static NSUInteger old_flags           = 0;
-            NSUInteger new_flags                  = event.modifierFlags;
+            NSUInteger new_flags                  = [event modifierFlags];
             NSUInteger changed_flags              = new_flags ^ old_flags;
-            uint16_t keycode                      = event.keyCode;
+            uint16_t keycode                      = [event keyCode];
             bool down                             = false;
 
             /* Determine if the changed modifier is being pressed or released
@@ -468,8 +467,8 @@ static ui_application_t ui_application_cocoa = {
         case NSEventTypeRightMouseDragged:
         case NSEventTypeOtherMouseDragged:
          {
-            CGFloat delta_x             = event.deltaX;
-            CGFloat delta_y             = event.deltaY;
+            CGFloat delta_x             = [event deltaX];
+            CGFloat delta_y             = [event deltaY];
             NSPoint pos                 = CONVERT_POINT();
             cocoa_input_data_t
                *apple                   = (cocoa_input_data_t*)
@@ -496,18 +495,14 @@ static ui_application_t ui_application_cocoa = {
             }
          }
          break;
-#if defined(HAVE_COCOA_METAL)
-        case NSEventTypeScrollWheel:
-#elif defined(HAVE_COCOA)
-        case NSScrollWheel:
-#endif
+      case NSEventTypeScrollWheel:
          /* TODO/FIXME - properly implement. */
          break;
        case NSEventTypeLeftMouseDown:
        case NSEventTypeRightMouseDown:
        case NSEventTypeOtherMouseDown:
        {
-           NSInteger number      = event.buttonNumber;
+           NSInteger number      = [event buttonNumber];
            NSPoint pos           = CONVERT_POINT();
            cocoa_input_data_t
               *apple             = (cocoa_input_data_t*)
@@ -522,7 +517,7 @@ static ui_application_t ui_application_cocoa = {
       case NSEventTypeRightMouseUp:
       case NSEventTypeOtherMouseUp:
          {
-            NSInteger number      = event.buttonNumber;
+            NSInteger number      = [event buttonNumber];
             NSPoint pos           = CONVERT_POINT();
             cocoa_input_data_t
               *apple              = (cocoa_input_data_t*)
@@ -1410,17 +1405,13 @@ static NSWindow *cocoa_create_main_window(void)
                     | NSWindowStyleMaskResizable;
    NSRect frame = NSMakeRect(0, 0, 480, 360);
 
-#ifdef HAVE_COCOA_METAL
+   /* Both HAVE_COCOA and HAVE_COCOA_METAL use RAWindow now; its
+    * -sendEvent: override is what feeds keyboard/mouse events into
+    * the cocoa_input driver. */
    NSWindow *window = [[RAWindow alloc] initWithContentRect:frame
                                                   styleMask:style
                                                     backing:NSBackingStoreBuffered
                                                       defer:NO];
-#else
-   NSWindow *window = [[NSWindow alloc] initWithContentRect:frame
-                                                  styleMask:style
-                                                    backing:NSBackingStoreBuffered
-                                                      defer:NO];
-#endif
    [window setTitle:@"RetroArch"];
    [window setReleasedWhenClosed:NO];
    [window setAllowsToolTipsWhenApplicationIsInactive:NO];