__btowc
extern wint_t __btowc(int c);
extern wint_t __btowc (int __c);
wint_t wc = __btowc (b);
wint_t wc = __btowc (br_elem->opr.ch);
ch_collseq = __collseq_table_lookup (collseqwc, __btowc (ch));
wint_t wch = __btowc (ch);
outchar (__btowc ((unsigned char) va_arg (ap, int))); /* Promoted. */ \
outchar (__btowc ((unsigned char) \
B_DEFINE_WEAK_ALIAS(__btowc, btowc);