Intends to replace: https://gitlab.winehq.org/wine/wine-staging/-/blob/master/patches/winex11-im...
This patch has been in proton for almost 2 years now, never realized the same code existed upstream, lol
-- v2: win32u/tests: Add test for multi-thread NotifyIME. winex11: Ensure initialized thread data in X11DRV_get_ic.