Fix SDL_SetWindowFullscreen error checking

Missed spot from SDL 3 migration. Both the fullscreen argument
(changed from flags to bool) and the return value (changed to bool)
were wrong. The flags mistake was harmless as it converted to the
correct bool value, but the error checking was unreachable.

Author: slipher

src/engine/sys/sdl_glimp.cpp

@@ -988,10 +988,7 @@ static bool GLimp_RecreateWindowWhenChange( const bool fullscreen, const bool bo
 
 	if ( fullscreen != currentFullscreen )
 	{
-		Uint32 flags = fullscreen ? SDL_WINDOW_FULLSCREEN : 0;
-		int sdlToggled = SDL_SetWindowFullscreen( window, flags );
-
-		if ( sdlToggled < 0 )
+		if ( !SDL_SetWindowFullscreen( window, fullscreen ) )
 		{
 			GLimp_DestroyWindowIfExists();
 
@@ -2914,7 +2911,6 @@ void GLimp_HandleCvars()
 
 	if ( Util::optional<bool> wantFullscreen = r_fullscreen.GetModifiedValue() )
 	{
-		int sdlToggled = false;
 		bool needToToggle = true;
 		bool fullscreen = !!( SDL_GetWindowFlags( window ) & SDL_WINDOW_FULLSCREEN );
 
@@ -2923,10 +2919,7 @@ void GLimp_HandleCvars()
 
 		if ( needToToggle )
 		{
-			Uint32 flags = *wantFullscreen ? SDL_WINDOW_FULLSCREEN : 0;
-			sdlToggled = SDL_SetWindowFullscreen( window, flags );
-
-			if ( sdlToggled < 0 )
+			if ( !SDL_SetWindowFullscreen( window, *wantFullscreen ) )
 			{
 				Log::Warn( "SDL_SetWindowFullscreen failed: %s", SDL_GetError() );
 				Log::Warn( "Trying vid_restart" );