[Patch] Change _M_overflow to call _M_convert_to_external once

[Nathan Myers]

I wrote:
> I would rather see setbuf(p,1) be equivalent to setbuf(0,0) than to 
> simply ignore it.  However, I don't see this as a reason to hold off 
> applying the patch as is, and then tweaking that later.

Of course what I meant to say was, "However, I don't see this as a 
reason to hold off applying the patch as is; we can tweak that later.

Nathan Myers
ncm-nospam@cantrip.org