patches for threads/eh, tuning, etc

[Loren James Rittle]

> Cool. I'm almost done with some of the GNATS triage, but I too am leaving 
> soon for critical mass and other non-work stuff. 

> Next up for me is libstdc++/2346, and then I'd like to work with you on 
> the solaris fseek issue when this threads/eh bit is done. Sound good?

Sounds good to me.  I am working on threading issues in libstdc++
again today.  To get back to your last request, here is how I can
break the patch apart:

- _USE_MALLOC configuration patch.  (Done and regression tested in
  two+ environments.)

- Fix C++ EH (which already uses gthr.h) to work properly in light of
  threading.  (Done and regression tested in two+ environments, except
  requires Makefile.in, etc. change at higher level.)

- Use gthr.h abstraction layer in libstdc++-v3 instead of reinventing
  thread support.  (Some implementation work remains to install
  properly and to use gthr.h provided mutex locks in STL.)

Regards,
Loren