Where appropriate, use the modern terms for the one true time base
(UTC) rather than the archaic (GMT) in comments. Except where the
comments are making fun of people doing this (and pedants who insist
on the new terms).
Fix various mdoc issues.

Found with:	mandoc -Tlint
Remove EOL whitespace.

Found with:	mandoc -Tlint
Fix various mdoc issues and some EOL whitespace.

Found with:	mandoc -Tlint
Merge remote-tracking branch 'freebsd/master' into hardened/current/master