Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.

Start the dreaded NOFOO -> NO_FOO conversion.

OK'ed by: core

For variables that are only checked with defined(), don't provide
any fake value.

Add a simple exercise suite for IP-level socket options. The suite
atempts to read and write various IP-level socket options as root and
nobody, making sure the initial values are as expected, that they can
be changed to valid values and take effect, etc. No attempt is made
to check for the correct implementation of side effects (such as
changes in packet headers) as yet.

The IP options section is currently broken but will be fixed shortly.

Not all multicast options are currently tested.