pthread related breakage (mainline)

[Paolo Carlini]

Jason Merrill wrote:

>I think it is--I think your overload patch broke it.  The problem is that
>the #pragma weaks for the pthread functions are now being ignored, because
>handle_pragma_weak expects an affected function to be the
>identifier_global_value of its name, and now it isn't.
>  
>
Ah!

*Many* thanks Jason and sorry Nathanael for having suspected your 
changes... I couldn't imagine an interaction between threads and the C++ 
front end, poor me...

Paolo.