Do not restart services of different architecture than libc

Only check services in packages which are of the same architecture, or
"arch:all".  This is most easily done by replacing the rather
convoluted way of parsing "dpkg --status" output by switching to a
more suitable output format of dpkg-query.  As a bonus, awk is no
longer used in the maintscripts.

Note that services in architecture-independent packages like
postgresql-common will still be restarted twice, since there is no
obvious way to tell the architecture of the actual binaries which need
to be re-executed.