glx: Implement GLX_EXT_libglvndglx-ext-libglvnd

For the dri2 backend, we depend on xfree86 already, so we can walk the
options for the screen looking for a vendor string from xorg.conf.  For
the swrast backend we don't have that luxury, so just say mesa.  This
extension isn't really meaningful on Windows or OSX yet (since libglvnd
isn't really functional there yet), so on those platforms we don't say
anything and return BadValue for the token from QueryServerString.

Signed-off-by: Adam Jackson <ajax@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/glx/glxscreens.h b/glx/glxscreens.h
index c63fb5684..15196fa43 100644
--- a/glx/glxscreens.h
+++ b/glx/glxscreens.h
@@ -143,6 +143,7 @@ struct __GLXscreen {
 
     char *GLextensions;
     char *GLXextensions;
+    char *glvnd;
     unsigned char glx_enable_bits[__GLX_EXT_BYTES];
 
     Bool (*CloseScreen) (ScreenPtr pScreen);