Fixed a memory leak in function GL_RenderReadPixels

src/render/opengl/SDL_render_gl.c

@@ -1438,6 +1438,7 @@ GL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
     }
 
     if (!convert_format(data, temp_format, &internalFormat, &format, &type)) {
+        SDL_free(temp_pixels);
         return SDL_SetError("Texture format %s not supported by OpenGL",
                             SDL_GetPixelFormatName(temp_format));
     }