[Bug libstdc++/36231] ostream includes unistd.h outside namespace std, polluting

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36231

--- Comment #15 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-04-20 
20:36:30 UTC ---
Unfortunately the issue seems more complex, because gthr.h is dragged in also
via <string>, which is everywhere...