Add /usr/lib/debug directory to hier(7)

The canonical standalone debug directory established by the GNU
toolchain is /usr/lib/debug, and we use it when WITH_DEBUG_FILES is set.
Mention it in the file system hierarchy page.

Reviewed by:	bcr
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D1134
cxgbe(4): adjust PMRX and PMTX parameters.

MFC after:	1 week
sync a comment with our internal repo
initialize *color if passed as an argument
fix a typo
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/segvguard