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

free(3) won't mess with errno so return it as-is.

Submitted by: Jaakko Heinonen <jh saunalahti fi>

Split tolower/toupper code from usual xlat16 kiconv table, and make it
possible to do tolower/toupper independently without code conversion.

Submitted by: imura (but bugs are mine)
Obtained from: http://people.freebsd.org/~imura/kiconv/
(1_kiconv_wctype_kern.diff, 1_kiconv_wctype_user.diff)