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

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

Consistently set RPCGEN_CPP when running rpcgen, so the C preprocessor
set via ${CPP} is used, instead of always using hardcoded /usr/bin/cpp.

MFC after: 1 week

NOPAM -> NO_PAM

We no longer have KerberosIV. Remove it here also.

Add a few files which are needed to build "passwd" now that
the standard version of these files have been PAMified (and axed).

Bring in a slightly older version of usr/bin/passwd which does not
require libpam and all the libraries that libpam brings in.
We have no room for those on picobsd images.