Plug-in common/logging.h with vacuumlo and oid2name

Hi all,

While refactoring some code, I have bumped into $subject, which causes
both tools to have incorrect error message formats and progname being
used all through the code, sometimes incorrectly or just missing.

At the same time, we are missing a call to set_pglocale_pgservice()
for both binaries.

Any objections to the cleanup attached?
--
Michael