glx: Prepare the DRI backends for GLX_EXT_no_config_context

This should be safe as these backends already support the EGL version of
this extension. DRI1 is not affected because it does not support
GLX_ARB_create_context anyway. DRI-Windows is not prepared to implement
this as there's no equivalent WGL extension, and wglCreateContextAttribs
seems to really want the HDC's pixel format to be set.

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
3 files changed