Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

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

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

When WITH_ICONV is set, use our in-tree iconv.

Enable NLS catalog of csh(1).
The tcsh 6.14 uses libiconv to convert catalogs to appropriate charset
dynamically. However, we don't have libiconv in our tree. So, I made
some hack to load libiconv dynamically. If libiconv is available, you
can use catalogs for more locales than the locales which catalog is
actually installed.
To use this feature, you need to symlink catalogs to appropriate
locales. You can do this by installing ports/shells/tcsh_nls.

Reviewed by: arch (no objection)
MFC after: 1 week