Don't start running weird grep+awk commands on a directory that doesn't even exist (!)
I got this on Mac OS X. It has a /usr/share/zoneinfo/, but no zone.tab in there, nor anywhere else.
It has no /usr/share/lib/zoneinfo/src at all.

With this commit, m_zoneinfoDir is correctly set to that dir even though there's no zone.tab,
but I guess this won't really work? (I still get unit test failures)
Is it possible to support /usr/share/zoneinfo even without a zone.tab? Surely other
programs (from BSD, ported to Mac OS X) must manage somehow...