(svn r22893) -Fix [FS#4744]: [OSX] Compilation on OSX 10.7 was broken (based on patch by leecbaker)

-Add: [OSX] Support for fullscreen mode when compiled against SDK 10.7. Otherwise fullscreen mode is disabled when OpenTTD is run on OSX Lion

src/video/cocoa/cocoa_v.h

@@ -88,6 +88,7 @@ public:
 	virtual bool ChangeResolution(int w, int h) = 0;
 
 	virtual bool IsFullscreen() = 0;
+	virtual bool ToggleFullscreen() { return false; };
 	virtual int GetWidth() = 0;
 	virtual int GetHeight() = 0;
 	virtual void *GetPixelBuffer() = 0;