samples: add missing callbacks.h and Makefile

Fixes issue #2

sample/Makefile

@@ -0,0 +1,26 @@
+all:
+	make -C clock
+	make -C coordinates
+	make -C deform
+	make -C depth
+	make -C objcontrol
+	make -C screensaver
+	make -C transform
+
+clean:
+	make -C clock clean
+	make -C coordinates clean
+	make -C deform clean
+	make -C depth clean
+	make -C objcontrol clean
+	make -C screensaver clean
+	make -C transform clean
+
+install:
+	make -C clock install
+	make -C coordinates install
+	make -C deform install
+	make -C depth install
+	make -C objcontrol install
+	make -C screensaver install
+	make -C transform install

sample/callbacks.h

@@ -0,0 +1,38 @@
+#ifndef __CALLBACKS_H__
+#define __CALLBACKS_H__
+
+#include <pspkernel.h>
+
+int callbacks_exit()
+{
+    sceKernelExitGame();
+
+    return 0;
+}
+  
+int callbacks_thread()
+{
+    int id;
+    
+    id = sceKernelCreateCallback("exit_cb", callbacks_exit, NULL);
+    sceKernelRegisterExitCallback(id);
+    sceKernelSleepThreadCB();
+    
+    return 0;
+}
+  
+int callbacks_setup()
+{
+    int id;
+    
+    id = sceKernelCreateThread("cb", callbacks_thread, 0x11, 0xFA0, 0, NULL);
+    
+    if (id >= 0)
+    {
+        sceKernelStartThread(id, 0, NULL);
+    }
+    
+    return id;
+}
+
+#endif // __CALLBACKS_H__