* newlib.hin (_FVWRITE_IN_STREAMIO): Undefine.
* configure.in (--disable-newlib-fvwrite-in-streamio): New option.
* configure: Regenerated.
* libc/stdio/fputs.c (_fputs_r): Use _FVWRITE_IN_STREAMIO to
control __sfvwrite_r. Add alternative implementation.
* libc/stdio/fputws.c (_fputws_r): Ditto.
* libc/stdio/fwrite.c (_fwrite_r): Ditto.
* libc/stdio/puts.c (_puts_r): Ditto.
* libc/stdio/vfprintf.c (__ssputs_r, __sfputs_r): New function.
(_VFPRINTF_R): Use _FVWRITE_IN_STREAMIO to control vector buffer.
(__SPRINT): Use _FVWRITE_IN_STREAMIO to control macro definition.
* libc/stdio/vfwprintf.c (_VFWPRINTF_R): Use _FVWRITE_IN_STREAMIO
to control vector buffer.