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

Fix -Wunused warnings, bump WARNS to 6

The output is still broken if prove -rv is run and the testcase aborts
prematurely with fail_assertion (the testcase doesn't really conform to TAP
protocol properly, except when it completes fully)

MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division

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

Join the effort in simplifying this makefile. ;)

Don't override the rule used to build a binary by providing our own
compiler line.

Add a basic kqueue + UNIX domain socket pair regression test to do some
elementary exercising of kqueues on datagram and stream sockets. Note
that the datagram write kqueue case is left untested due to potentially
confusing behavior for the developer (me) that might require attention.