Unlike the previous implementation, this implementation is locked:
only one initialisation is ever run at the same time. It is
exception-safe, meaning that a throwing constructor will restart the
process.
Also, start using the thread-safe behaviour that GCC has offered for a
long time and C++11 requires.
Change-Id: I20db44f57d258923df64c0051358fd0d9a5ccd51
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: David Faure (KDE) <faure@kde.org>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
