mesa: create multisample fallback textures like normal textures
This works if drivers upsample on upload (like all radeon ones do).
The alternative is an unexpected GL error from anything calling
_mesa_update_state and possibly other issues.
Cc: 10.6 11.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by:
Dave Airlie <airlied@redhat.com>