meson: fix with_dri2 definition for GNU Hurd

Suggested-by: Dylan Baker <dylan@pnwbakers.com>
Cc: Timo Aaltonen <tjaalton@debian.org>
Cc: James Clarke <jrtc27@debian.org>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
25 jobs for !382 with meson-fix-hurd-dri2
detached