MFC r316022,r316023:

Fix hexadecimal escape codes in jail.conf(5).

PR: 218154
Submitted by: Masahiro Konishi <mkonishi@sea.plala.or.jp>

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

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

Work around build breakages with GCC 4.2.

Reported by: tinderbox

Improve compatibility with recent flex from flex.sourceforge.net.

Add YY_NO_INPUT so clang doesn't complain about "input" not being used.

A new jail(8) with a configuration file, ultimately to replace the work
currently done by /etc/rc.d/jail.

MFC after: 3 months

Update copyright dates and other whitespacey stuff.

Initial work on the new jail(8). There are more features to add, and some
cleaning up to do on existing features, but this is pretty much what the
final product will look like.