egl: implement __DRIbackgroundCallableExtension.isThreadSafe

v2:
bump version

v3:
Add code comment
s/IsGlThread/IsThread/ (and variation)
Include X11/Xlibint.h protected by ifdef

v5: based on Daniel feedback
Move non X11 code outside of X11 define
Always return true for Wayland

Signed-off-by: Gregory Hainaut <gregory.hainaut@gmail.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
1 file changed