GLX: DRI2: Fix mismatched-types warning

All the DRI extension types have a base extension type as their first
member to avoid exactly these types of warning.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Cyril Brulebois <kibi@debian.org>

glx/glxdri2.c

@@ -594,7 +594,7 @@ static const __DRIextension *loader_extensions[] = {
     &systemTimeExtension.base,
     &loaderExtension.base,
 #ifdef __DRI_USE_INVALIDATE
-    &dri2UseInvalidate,
+    &dri2UseInvalidate.base,
 #endif
     NULL
 };