overlay: re-introduce checks for 'debugoverlay' and 'nooverlay'.
overlay: re-introduce checks for 'debugoverlay' and 'nooverlay'.

These were removed when we removed all the legacy exclusion logic.
This commit re-adds them in a more sensible way.

Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble