libio: use stdout in puts and putchar, etc [BZ #24051].

libio: use stdout in puts and putchar, etc [BZ #24051].

GLIBC explicitly allows one to assign a new FILE pointer to stdout and
other standard streams.  printf and wprintf were honouring assignment to
stdout and using the new value, but puts, putchar, and wide char variants
did not.

The stdout part is fixed here.  The stdin part will be fixed in a followup.