gitlab migration: xserver issues enabled

[Adam Jackson]

I've enabled filing gitlab issues for xserver, as people were trying to
file bugs against xorg/meta (which is not the right place). Expect
bugzilla migration to start happening later this week and take... well,
I don't know how long, I'll be attempting to triage/close old issues as
I go and I don't have a good estimate for how long that'll take. If
you're getting notifications for xorg issues from gitlab, and haven't
set up your mail filters yet, now would be an excellent time to do
that.

- ajax