Change msgfmt to produce little-endian .mo files by default.
* gettext-tools/src/msgfmt.c (main): Initialize 'byteswap' so as to
produce little-endian .mo files by default.
* gettext-tools/doc/gettext.texi: Update documentation.
* gettext-tools/doc/msgfmt.texi (--endianness): Likewise.
