mesa: Disable glthread when glBegin() is called.

glBegin() swaps dispatch tables, and we don't have any code in place for
handling that in glthread (which also messes with dispatch tables), and I
don't particularly care to at this point.

Acked-by: Timothy Arceri <tarceri@itsqueeze.com>
Acked-by: Marek Olšák <maraeo@gmail.com>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
1 file changed