Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

kqueue tests: Simplify the test runner

Just invoke the test program directly instead of trying to convert its
output to TAP format. The test suite is all or nothing; there's no way
to enumerate individual test cases, so there's no advantage in trying to
massage its output, and doing so throws away information that's useful
when diagnosing test failures.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

Fix various warnings in tests/sys/kqueue and bump WARNS

Reviewed By: kevans
Differential Revision: https://reviews.freebsd.org/D24296

Move tests/sys/kqueue/... to tests/sys/kqueue/libkqueue/...

This is being done to clearly distinguish the libkqueue tests
from the (soon to be imported) NetBSD tests.

MFC after: 58 days
Sponsored by: EMC / Isilon Storage Division