Fix compile warnings on 10.6

Apple clang 3.0 complains about missing function
declarations. Add them.

Change-Id: Ib9c3c238c94e8649844cf3e67a659875ad549ecb
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>

src/plugins/platforms/cocoa/qcocoacolordialoghelper.mm

@@ -82,6 +82,7 @@ static NSButton *macCreateButton(const char *text, NSView *superview)
     BOOL mDialogIsExecuting;
     BOOL mResultSet;
 };
+- (void)restoreOriginalContentView;
 - (void)relayout;
 - (void)updateQtColor;
 - (void)finishOffWithCode:(NSInteger)code;

src/plugins/platforms/cocoa/qcocoafontdialoghelper.mm

@@ -121,6 +121,7 @@ static QFont qfontForCocoaFont(NSFont *cocoaFont, const QFont &resolveFont)
     BOOL mDialogIsExecuting;
     BOOL mResultSet;
 };
+- (void)restoreOriginalContentView;
 - (void)relayout;
 - (void)relayoutToContentSize:(NSSize)frameSize;
 - (void)updateQtFont;

src/plugins/platforms/cocoa/qcocoamenu.mm

@@ -84,6 +84,7 @@ static inline QCocoaMenuLoader *getMenuLoader()
 }
 
 - (id) initWithMenu:(QCocoaMenu*) m;
+- (BOOL)hasShortcut:(NSMenu *)menu forKey:(NSString *)key forModifiers:(NSUInteger)modifier;
 
 @end