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>
5 jobs for glx-context in 7 minutes and 25 seconds (queued for 1 second)
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passed debian-buster #10574017

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  Build And Test
passed autotools #10574018

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passed meson #10574019

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passed meson-noglamor #10574020

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passed mingw-cross-build #10574021

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