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

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

On FreeBSD just use the MD5 implementation of libmd rather than that of
libcrypto so we don't need to relinquish csup when world is built without
OpenSSL.

- Include CURDIR in case the makefile is not run from the same directory.

- Remove unused include path.

- Revert Makefile to revision r203368, as the svn mv from contrib/csup replaced
the Makefile with a broken version.

- 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

- Add support for CVSup authentication mechanisms to csup.
- Include a cpasswd script performing the same mechanisms as the cvpasswd
utility from CVSup.

PR: bin/114129
Submitted by: Petar Zhivkov Petrov <pesho.petrov -at- gmail.com>
MFC after: 1 month

Merge support for CVSMode (aka. mirror mode) into csup. This means csup can now
fetch a complete CVS repository. Support for rsync update of regular files are
also included, but are not yet enabled. The change should not have an impact on
existing csup usage, as little of the existing code has changed.

This commit was generated by cvs2svn to compensate for changes in r156701,
which included commits to RCS files with non-trunk default branches.

Import the latest snapshot of csup (20060313).

Initial import of csup.