c/manpages.pm: Check if manapage name include buildd

Example:
    usr/share/man/man3/_build_buildd-openchange_1.0-3-i386-mbKpOA_openchange-1.0_doc_.3.gz

[nthykier: rename tag and reword description]

Signed-off-by: Niels Thykier <niels@thykier.net>
d/changelog: Add systemd tags to tag summary

Signed-off-by: Niels Thykier <niels@thykier.net>