[libstdc++ PATH] tr1::bind support

[Benjamin Kosnik]

> One 
> "minor" difference between the libstdc++ and Boost implementations of 
> bind and mem_fn is that libstdc++ uses a single class template (e.g., 
> _Bind) with lots of partial specializations whereas Boost uses many 
> more class templates with the number of parameters attached (bind0, 
> bind1, bind2, ..., etc.). We could try going the Boost way to see if 
> that improves compile time.

For what it's worth, I prefer the partial specialization approach. I think it
much more elegant: nice stylish job. 

Wouldn't adding the tr1 headers to the pch file give us a bigger boost?
Chris seemed to indicate this, at least, in a prior message. I'm in
favor of that.

-benjamin