MFC all features as of r248336:

The user visable feature is from r246083:

Add -l option to cat(1). This option causes cat(1) to use fcntl(2) to
set an exclusive advisory lock on stdout.  This will be used to guarantee
orderly writing to METALOG.

Sponsored by:	DARPA, AFRL
Obtained from:	NetBSD (mason)
Bump __FreeBSD_version for install -l, -M, -N and related flags as well
as cat -l.

This is a notional MFC of r245313,246084.
MFC r245513,245514,245515:

The last section 1aout manpage was installed no later than July 2002.
Remove all support for them.