Fixed building with the 10.10 SDK

src/video/cocoa/SDL_cocoawindow.m

@@ -1356,10 +1356,12 @@ Cocoa_CreateWindow(_THIS, SDL_Window * window)
         return SDL_SetError("%s", [[e reason] UTF8String]);
     }
 
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= 101200 /* Added in the 10.12.0 SDK. */
     /* By default, don't allow users to make our window tabbed in 10.12 or later */
     if ([nswindow respondsToSelector:@selector(setTabbingMode:)]) {
         [nswindow setTabbingMode:NSWindowTabbingModeDisallowed];
     }
+#endif
 
     if (videodata->allow_spaces) {
         SDL_assert(floor(NSAppKitVersionNumber) > NSAppKitVersionNumber10_6);