MFC r288266:

Add more SUBDIR_PARALLEL.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Clean up makefiles and a manpage.

OK'ed by: phk

Add the fifolog tools to FreeBSD.

Quoth the man-page:

Fifologs provide a compact round-robin circular storage for recording
text and binary information to permanent storage in a bounded and pre-
dictable fashion, time and space wise.

Not yet connected to the build, but feel free to test & review.