When a drawable goes away, we don't destroy the GLX drawable in full,
since it may be current for a context. This means that when the drawable
is destroyed in full later, the backend doesn't get a chance to
destroy resources associated with the drawable (the DRI2Drawable).
With this patch, we destroy the GLX drawable in full when it goes away
and then track down all contexts that reference it and NULL their
pointers.
Using GL for the PKG_CHECK_MODULES identifier multiple times means only
the first call will actually be used. Later calls will be skipped due to
GL_CFLAGS and GL_LIBS already being set. This changes DRI to using a
different identifier and DMX to just reusing GL_CFLAGS.
Signed-off-by: Dan Nicholson <dbn.lists@gmail.com>
