intel: Remove NV_vertex_program support.

intel: Remove NV_vertex_program support.

We were holding on to this code because we were aware that NWN 1 had some
support for vertex programs -- no other linux programs I've come across would
use it (since other software also has ARB_vp or GLSL support).  Only, it turns
out that NWN doesn't even give us any vertex programs.  Given that we have
known issues where the extension has never been fully supported, just give up
on it.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=46795
Reviewed-by: Brian Paul <brianp@vmware.com>