GObject: workaround for double __del__ calling
GObject: workaround for double __del__ calling

There are scenarios when the reference to the object can be obtained
from the different thread while the object in the process of tearing down.
In that case the __del__ can be called twice. We explode on the second call
to __del__ while trying to get 'g_type' field of the object which was
already freed. This workaround prevents us from exploding. Unfortunately we
would still explode trying to access the internals of freed object from
any other function. Hope it will not happen.

pexip/pygobject,pexip/pygobject,pexip/pygobject