glx: Set ContextTag for all contexts

Currently, xorgGlxMakeCurrent() would set the context tag only for
indirect GLX contexts.

However, several other places expect to find a context for the tag or
they would raise a GLXBadContextTag error, such as WaitGL() or WaitX().

Set the context tag for direct contexts as well, to avoid raising an
error and possibly killing the client.

Thanks to Erik Kurzinger <ekurzinger@nvidia.com> for spotting the issue.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
(cherry picked from commit c468d34c)
3 jobs for xwayland-21.1-eglstream in 3 minutes and 53 seconds
Status Job ID Name Coverage
  Docker Image
passed #10575803
debian-buster

00:00:42

 
  Build And Test
passed #10575804
meson

00:03:10

passed #10575805
meson-noglamor

00:03:10