Code review request: small optimization to localtime.c

[M. Warner Losh]

In message: <20071128221724.GS71382 at elvis.mu.org>
            Alfred Perlstein <alfred at freebsd.org> writes:
: See pthread_once...

Good point.  Much of the time code tries hard to avoid thread related
things, but in all but one of these cases pthread_once() would be
better than what's there now.

Warner