dri2: do not conflate unbind and bindContext() failure

dri2_make_current() has become hard to follow, address this by
splitting the semantic of needing a call to bindContext() and
its failure.

Cc: mesa-stable
Signed-off-by: Luigi Santivetti <luigi.santivetti@imgtec.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5707>
1 file changed