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

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

- Move csup away from contrib/ and into usr.bin/. Software is no longer
contributed, and main development is happening in the FreeBSD repo.

Suggested by: joel

This commit was generated by cvs2svn to compensate for changes in r169765,
which included commits to RCS files with non-trunk default branches.

Fix a typo that caused the #undef directive to not actually undefine
the correct symbol, thus causing a warning with GCC 4.2.0. Committed
into the vendor branch since this is already in the csup repository.

Reported by: kan (ages ago)

Import today's csup sources to get the warning fix for queue.h. We
probably want to do something similar in sys/queue.h; it's bad to have
STAILQ_LAST() generate GCC warnings.

Initial import of csup.