mi_sprintf_putc
count = mi_iprintf(fmt, ap, (pfi_t)mi_sprintf_putc,
(void) mi_sprintf_putc((char *)&buf, '\0');
count = mi_iprintf(fmt, ap, mi_sprintf_putc, (char *)&cp);
(void) mi_sprintf_putc((char *)&cp, '\0');
extern int mi_sprintf_putc(char *cookie, int ch);