Maek init_global_thread_specific_state as a constructor to try and ensure

Maek init_global_thread_specific_state as a constructor to try and ensure
that it is called as soon as libpthread.so is loaded even if pthread_create
is never called.

This ensures that pthread_exit will work correctly, and I think will also
cure the famous memory leak in the pthread specifics for the main thread.

CCMAIL: 86730-done@bugs.kde.org

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2584