Log Message:
fix the DESTDIR support by removing the install-root target which
would otherwise cause a chown of the trigger file. (with DESTDIR,
the "nullmail" user & group are not yet created)

Because this leaves the trigger file possibly owned by root, add
a test in the rc "start" path to [re]make it when necessary.

put this test and the daemon background and logging into a
separate script so that it can be run by the rc framework as the
nullmail user in the normal way, and add a procname argument to
allow the "status" and "stop" rc commands to work properly.

bump PKGREVISION