Fixed wrong pixel format if reading pixels from OpenGL renderer.

src/render/opengl/SDL_render_gl.c

@@ -1422,7 +1422,7 @@ GL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
                     Uint32 pixel_format, void * pixels, int pitch)
 {
     GL_RenderData *data = (GL_RenderData *) renderer->driverdata;
-    Uint32 temp_format = renderer->target ? renderer->target->format : SDL_PIXELFORMAT_ABGR8888;
+    Uint32 temp_format = renderer->target ? renderer->target->format : SDL_PIXELFORMAT_ARGB8888;
     void *temp_pixels;
     int temp_pitch;
     GLint internalFormat;