Give base manual page higher priority than ports manual pages

First look in the FreeBSD base manual pages (aka /usr/share/man) and then
in FreeBSD ports (aka /usr/local/man). This avoids confusion when manual pages have
have the same name, but are in different sections. In this case, a ports manual
pages would win because of the higher section priority. Now, searching for "socket"
will always show socket(2) from the base system and not socket(1) from ports

PR: 264054
Reported by: grog