Fix SDL_BlitSurfaceScaled crash

SDL_BlitSurfaceScaled could crash when passed large coordinates, due
to final_dst.w or final_dst.h getting negative values.

src/video/SDL_surface.c

@@ -1256,7 +1256,7 @@ bool SDL_BlitSurfaceScaled(SDL_Surface *src, const SDL_Rect *srcrect, SDL_Surfac
     // Clip again
     SDL_GetRectIntersection(clip_rect, &final_dst, &final_dst);
 
-    if (final_dst.w == 0 || final_dst.h == 0 ||
+    if (final_dst.w <= 0 || final_dst.h <= 0 ||
         final_src.w < 0 || final_src.h < 0) {
         // No-op.
         return true;