Log message:
Add RMD160 digests.

Log message:
Import crypto++ from pkgsrc-wip.  Packaged by Sergio Jimenez and
slightly modified by me.

Crypto++ Library is a free C++ class library of cryptographic schemes.
One purpose of Crypto++ is to act as a repository of public domain
(not copyrighted) source code.  Although the library is copyrighted as
a compilation, the individual files in it (except for a few exceptions
listed in the license) are in the public domain.