Libstdc++ thread-unsafe statics audit

[Nathan Myers]

I just did an audit of the use of local statics in libstdc++.
I was checking for uses of nontrivial initializers that would be
inherently unsafe in a threaded environment.  

I looked for the word "static" in all files (before configure) 
whose names fit the pattern *.h, *.tcc, or *.cc.

I didn't find any violations.  It is possible that some of 
libsupc++/eh_*.cc could have violations for some possible definitions 
of __GTHREAD_ONCE_INIT, but I see it as the responsibility of whoever 
defines that macro to do the right thing.

Nathan Myers
ncm at cantrip dot org