The platform headers has the following macro:
#define MB_CUR_MAX __ctype_get_mb_cur_max()
where __ctype_get_mb_cur_max() tries to handle UTF-8 encodings.
However, even in Android 7.0 setlocale(LC_ALL, ""), which many
programs do at startup, doesn't work in that it sets the locale
as non-utf8:
https://android.googlesource.com/platform/bionic/+/nougat-release/libc/bionic/locale.cpp#139
So we just always consider us being in an utf-8 locale.
Also rebuild coreutils to fix#1136.
