Get a file descriptor for manual event polling

[bl4ckb0ne]

Right now the only way to get the events is to call the function xrPollEvent. It would be quite handy to be able to retrieve a pollable file descriptor (FD for short) from OpenXR and integrate it into another event loop, such as wayland or simply epoll.

I would be interested to work on such extension, if it is deemed useful.

[rpavlik-bot]

An issue (number 1723) has been filed to correspond to this issue in the internal Khronos GitLab (Khronos members only: KHR:openxr/openxr#1723 ), to facilitate working group processes.

This GitHub issue will continue to be the main site of discussion.