Avoid duplicated iteration over services when announcing

Avoid duplicated iteration over services when announcing

In function service_announce_services we iterate over services and
handle every single one so calling service_reply which also iterates
doesn't make sense.

In simple cases it was just wasting CPU cycles. We got service, we were
passing its name and we were looking for it again comparing names.
In cases with one service available on few different ports it was worse.
For every iterated service we were announcing that one and all other
sharing the same name. It resulted in sending n^2 records.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: John Crispin <john@phrozen.org>