log: Make G_MESSAGES_DEBUG=something work out of the box
calls wouldn't match the glib docs as setting G_MESSAGES_DEBUG
also required to pass -vvv for things to work. Enable debug logs
as soon as that variable is set.
Closes: #720 (closed)
I think this could still be improved to make -vvv mean G_MESSAGES_DEBUG=all but this way things at least don't get lost when setting G_MESSAGES_DEBUG.