render: only enable clipping when the rectangle is valid

Fixes https://github.com/libsdl-org/SDL/issues/6896

(cherry picked from commit 00f05dcf49602889733262fc810386592ff51736)

src/render/SDL_render.c

@@ -2488,7 +2488,7 @@ int SDL_RenderSetClipRect(SDL_Renderer *renderer, const SDL_Rect *rect)
     int retval;
     CHECK_RENDERER_MAGIC(renderer, -1)
 
-    if (rect) {
+    if (rect && rect->w > 0 && rect->h > 0) {
         renderer->clipping_enabled = SDL_TRUE;
         renderer->clip_rect.x = (double)rect->x * renderer->scale.x;
         renderer->clip_rect.y = (double)rect->y * renderer->scale.y;