Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

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

Fixes to get rid of CD_HACK.

bsd.doc.mk changes:

Don't gratuitously pipe thru a cat(1) if NODOCCOMPRESS.

Only create _stamp.extra when necessary.

Get rid of SOELIMPP and OBJS.

Use Groff version of soelim(1); we need its -I option
for the following to work.

Don't needlessly chdir to SRCDIR. Only a few documents
need CD_HACK, and those that need it either use refer(1)
or .PSPIC macro which internally uses the .psbb call.

Groff 1.16.1 implements .psbb request internally in troff(1)
rather than as a macro using the .sy request, so we may drop
the unsafe (-U) mode.

Make this paper buildable in nroff mode, eliminate warnings,
do not force default printing device and compression mode.

The Jail paper, written jointly by rwatson & me.