Update.
* iconv/gconv_builtin.c: Include <endian.h>.
* iconv/gconv_builtin.h: Add UCS-BE aliases.
Add UCS-4LE transformation. Define UNICODEBIG and UNICODELITTLE
according to current platform.
* iconv/gconv_int.h: Declare __gconv_transform_ucs2reverse_internal,
__gconv_transform_internal_ucs2reverse, and
__gconv_transform_internal_ucs4le.
* iconv/gconv_simple.c: Implement __gconv_transform_internal_ucs4le,
__gconv_transform_ucs2reverse_internal and
__gconv_transform_internal_ucs2reverse.
* iconvdata/Makefile (modules): Add UNICODE.
(distribute): Add unicode.c.
* iconvdata/gconv-modules: Add definitions for UNICODE module.
* iconvdata/unicode.c: New file.
* iconvdata/utf-16.c: Rewrite code to emit BOM. Correct code to
determine byte order of input and convert accordingly.