Stefan Ekenberg authored Jun 03, 2015 and Matthias Clasen committed Jun 04, 2015

Prevents race condition in function g_io_condition_get_type by ensuring
that the initialization section for 'etype' is executed only once
during a program's life time, and that concurrent threads are blocked
until initialization completes. This changes solves the problem that
concurrent threads could execute the check 'etype == 0' before any of
them had initialized it, which in turn meant that multiple threads
would then attempt to register the "GIOCondition" type.

https://bugzilla.gnome.org/show_bug.cgi?id=750386