PATCH: profile mode fix for threads on solaris and cleanup

[Paolo Carlini]

Hi,
> Summary:
>
> - Fix 43259 by using __gnu_cxx::__mutex instead of fiddling with macro names.
> - Remove all calls to setenv.
>   
While I review the patch, please also provide a much smaller patch for
4.5.1 including only the above two sets of changes, as agreed in audit
trail.

Thanks,
Paolo.