winrt: Removed WinRT/Windows Phone/UWP support.

Fixes #10724.

src/render/opengles2/SDL_render_gles2.c

@@ -2040,16 +2040,6 @@ static bool GLES2_SetVSync(SDL_Renderer *renderer, const int vsync)
 {
     int interval = 0;
 
-#ifdef SDL_PLATFORM_WINRT
-    /* DLudwig, 2013-11-29: ANGLE for WinRT doesn't seem to work unless VSync
-     * is turned on.  Not doing so will freeze the screen's contents to that
-     * of the first drawn frame.
-     */
-    if (vsync == 0) {
-        return SDL_Unsupported();
-    }
-#endif
-
     if (!SDL_GL_SetSwapInterval(vsync)) {
         return false;
     }