[v3] c++0x <mutex> and <condition_variable>

[Paolo Carlini]

-- Chris,

I think that in principle <mutex> and <condition_variable> should be 
available also when __GTHREADS is undefined, that is plain single 
thread, in a trivial form of course (see for example ext/concurrence.h). 
Can you imagine anything smart here, better than sprinkling tons of #if 
__GTHREADS  everywhere? If we can do that, we have also to adjust 
[GLIBCXX_CHECK_GTHREADS] to immediately succeed as soon  as __GTHREADS 
is undefined.

Much lower priority than <thread>, to be clear ;)

Paolo.