[Piglit] [PATCH] glx: make sure contexts are destroyed before we exit the test

[Adam Jackson]

On Fri, 2019-04-12 at 16:23 +1000, Timothy Arceri wrote:
> Without this the last two contexts that are created will not
> have been destroyed when exiting the test. This creates a race
> condition in Mesa between any threads that might be using
> glsl_types and the atexit() callback that destroys these types.

Super minor nit: the commit summary line should perhaps say "unbound"
not "destroyed", since this change is not destroying them, simply
making sure that glXDestroyContext _will_ destroy them.

- ajax