Don't do NULL-checks before SDL_free()

Replaces the pattern

  if (ptr) {
    SDL_free(ptr);
  }

with

  SDL_free(ptr);

test/testutils.c

@@ -123,8 +123,6 @@ SDL_Texture *LoadTexture(SDL_Renderer *renderer, const char *file, bool transpar
         }
     }
     SDL_DestroySurface(temp);
-    if (path) {
-        SDL_free(path);
-    }
+    SDL_free(path);
     return texture;
 }