Any flags specified as well as "all" are subtracted from the result,
allowing the user to specify FOO_DEBUG="all,bar,baz" to mean "give me
debugging information for everything except bar and baz".
https://bugzilla.gnome.org/show_bug.cgi?id=642452
Instead of running the GPrivate destructors from our thread proxy code,
run it from the DllMain handler for the DLL_THREAD_DETACH case.
This should ensure that thread-local data is free at the exit of all
threads -- not just the ones we created for ourselves.
https://bugzilla.gnome.org/show_bug.cgi?id=660745