libobs: Move position for calling execute_graphics_tasks

The new order is as below:
[message pump]
output_frame
render_displays
execute_graphics_tasks

libobs/obs-video.c

@@ -964,8 +964,6 @@ bool obs_graphics_thread_loop(struct obs_graphics_context *context)
 		tick_sources(obs->video.video_time, context->last_time);
 	profile_end(tick_sources_name);
 
-	execute_graphics_tasks();
-
 #ifdef _WIN32
 	MSG msg;
 	while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
@@ -982,6 +980,8 @@ bool obs_graphics_thread_loop(struct obs_graphics_context *context)
 	render_displays();
 	profile_end(render_displays_name);
 
+	execute_graphics_tasks();
+
 	frame_time_ns = os_gettime_ns() - frame_start;
 
 	profile_end(context->video_thread_name);