Disallow overriding exec() in GL tests.
Disallow overriding exec() in GL tests.

MiUishadow/magnum,ashimidashajia/magnum,ashimidashajia/magnum,MiUishadow/magnum,ashimidashajia/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,DerThorsten/magnum,DerThorsten/magnum,DerThorsten/magnum,MiUishadow/magnum,DerThorsten/magnum,ashimidashajia/magnum,DerThorsten/magnum,ashimidashajia/magnum