mail/spamassassin*: Ensure process name is renamed even in debug mode

Some customers run spamassassin in debug mode. This breaks rc's ability
to manage the process because the process name is unexpectedly "perl".
When in debug mode, also set the process name to spamd.

Reported by: Dan Mahoney <danm@prime.gushi.org>
Upstream bug: https://bz.apache.org/SpamAssassin/show_bug.cgi?id=8384