_mbtowc_r with direct call to __mbtowc.
* libc/stdio/vfscanf.c: Ditto.
* libc/stdlib/btowc.c: Include local.h. Replace call to _mbtowc_r
with direct call to __mbtowc.
* libc/stdlib/mblen.c: Ditto.
* libc/stdlib/mblen_r.c: Ditto.
* libc/stdlib/mbrtowc.c: Ditto.
* libc/stdlib/mbstowcs_r.c: Ditto.
* libc/stdlib/mbtowc.c: Ditto.
* libc/stdlib/wcrtomb.c: Include local.h. Replace call to _wctomb_r
with direct call to __wctomb.
* libc/stdlib/wcsnrtombs.c: Ditto.
(_wcsnrtombs_r): Ditto.
* libc/stdlib/wcstombs_r.c: Ditto.
* libc/stdlib/wctob.c: Ditto.
* libc/stdlib/wctomb.c: Ditto.
* libc/stdlib/mbrtowc.c (mbrtowc): Implement independently from
_mbrtowc_r, unless PREFER_SIZE_OVER_SPEED or __OPTIMIZE_SIZE__ are
defined.
* libc/stdlib/wcrtomb.c (wcrtomb): Implement independently from
_wcrtomb_r, unless PREFER_SIZE_OVER_SPEED or __OPTIMIZE_SIZE__ are
defined.
* libc/stdlib/mbtowc_r.c (__utf8_mbtowc): Drop unnecessary test for
ch >= 0.