Fixed build after d0bbfdbfb8

src/video/SDL_bmp.c

@@ -697,8 +697,8 @@ int SDL_SaveBMP_RW(SDL_Surface *surface, SDL_RWops *dst, int freedst)
             } else {
                 SDL_InitFormat(&format, SDL_PIXELFORMAT_BGR24);
             }
-            surface = SDL_ConvertSurface(saveme, &format, 0);
+            intermediate_surface = SDL_ConvertSurface(surface, &format, 0);
-            if (surface == NULL) {
+            if (intermediate_surface == NULL) {
                 SDL_SetError("Couldn't convert image to %d bpp",
                              format.BitsPerPixel);
             }