gcc-3_0-branch cstdio=libio == libstdc++ doing miserable on makecheck

[Benjamin Kosnik]

> I cannot believe this.  The main advantage of libio is that you don't
> have to unbuffer the C library stdin, stdout, stderr streams to enable
> correct synchronization.  Unless you conditionally drop this
> requirement you'll have bad performance problems.

as in, this was the only performace degredation noted.

-benjamin