macosx: fixed compilation issue on Leopard

modules/gui/macosx/CompatibilityFixes.h

 /*****************************************************************************
  * CompatibilityFixes.h: MacOS X interface module
  *****************************************************************************
- * Copyright (C) 2011 VLC authors and VideoLAN
+ * Copyright (C) 2011-2012 VLC authors and VideoLAN
  * $Id$
  *
  * Authors: Felix Paul Kühne <fkuehne -at- videolan -dot- org>
@@ -63,9 +63,15 @@ extern OSErr UpdateSystemActivity(UInt8 activity);
 #define UsrActivity 1
 #endif
 
+/* the following is just to fix warnings, not for implementation! */
 @interface NSMenu (IntroducedInSnowLeopard)
 - (void)removeAllItems;
 @end
+
+@interface NSApplication (IntroducedInSnowLeopard)
+- (NSApplicationPresentationOptions)presentationOptions;
+- (void)setPresentationOptions:(NSApplicationPresentationOptions)newOptions;
+@end
 #endif
 
 #pragma mark -