Revert commit 790fa3156cfee847a7c0b34986de0cd7fdd7438f.

SDL_BLENDMODE_INVALID case is probably used for custom blendmode

src/render/SDL_render.c

@@ -1206,9 +1206,6 @@ IsSupportedBlendMode(SDL_Renderer * renderer, SDL_BlendMode blendMode)
     case SDL_BLENDMODE_MUL:
         return SDL_TRUE;
 
-    case SDL_BLENDMODE_INVALID:
-        return SDL_FALSE;
-
     default:
         return renderer->SupportsBlendMode && renderer->SupportsBlendMode(renderer, blendMode);
     }