pwd_mkdb, etc. updates at the end of the comparison.
2. Add an update to the end to handle /etc/localtime, if it exists.
If /var/db/zoneinfo exists, automatically update /etc/localtime,
which should (hopefully) be safe to do. If not, prompt the user
to run tzsetup.
3. Update run_it_now(), the function that handles input for the updates,
to make sure that we got a valid answer, and to handle the --run-updates
option if supplied.