Deleting a graph will mess with Godot rendering

[j20001970]

Symptom: deleting a graph object will break Godot's rendering.

• On desktop linux, it become unresponsive while other systems like audio are still working, but no error message observed in editor or stderr.
• On Android, it's the same except the screen become blank and produced a EGL_BAD_DISPLAY error in logcat.

The current workaround is to not deleting the graph object, but definitively not the best way as every created graph will pile up memory usage and probably slow down performance until restart.

I have no idea how to further debugging this for now, probably require someone who is more experienced to troubleshoot the issue.

[j20001970]

The issue has been (kind of) fixed in 0e0175a by stopping the graph in a std::thread.
Although I have no idea why it would work and EGL_BAD_DISPLAY error still present on Android, now Godot's rendering still works after stopping a graph or even explicit deleting it, tested on both desktop Linux and Android, so the issue will be closed.