Backport fix for exposing core and ES contexts on Xwayland to the next stable release

[Emmanuel Gil Peyrot]

Hello,

The current stable Xorg server release, 1.17.2, doesn’t support the
creation of a core profile OpenGL context, or of a GLES context, only
exposing compatibility profiles instead (so 3.0 on Mesa, see [1]).

This is a request to cherry-pick commit 2d719433 [2] from master to the
next 1.17 branch release.

Tested-by: Emmanuel Gil Peyrot <emmanuel.peyrot at collabora.com>

[1] https://bugs.freedesktop.org/show_bug.cgi?id=92218
[2] http://cgit.freedesktop.org/xorg/xserver/commit/?id=2d719433

Thanks,

-- 
Emmanuel Gil Peyrot
Collabora Ltd.