LibC: Align LOCK_* with various other impls

Same motivation as the previous commit.

Userland/Libraries/LibC/sys/file.cpp

@@ -14,8 +14,13 @@ extern "C" {
 
 int flock(int fd, int operation)
 {
+    short type = F_RDLCK;
+    if (operation & LOCK_UN)
+        type = F_UNLCK;
+    else if (operation & LOCK_EX)
+        type = F_WRLCK;
     struct flock lock {
-        short(operation & 0b11), SEEK_SET, 0, 0, 0
+        type, SEEK_SET, 0, 0, 0
     };
     return fcntl(fd, (operation & LOCK_NB) ? F_SETLK : F_SETLKW, &lock);
 }

Userland/Libraries/LibC/sys/file.h

@@ -10,10 +10,10 @@
 
 __BEGIN_DECLS
 
-#define LOCK_SH 0
-#define LOCK_EX 1
-#define LOCK_UN 2
+#define LOCK_SH (1 << 0)
+#define LOCK_EX (1 << 1)
 #define LOCK_NB (1 << 2)
+#define LOCK_UN (1 << 3)
 
 int flock(int fd, int operation);