fd.o #10613: tp_base_connection_unregister: release object path before bus name
fd.o #10613: tp_base_connection_unregister: release object path before bus name

We're effectively using the bus name as a mutex to protect the object
path, because dbus-glib doesn't have failable object path acquisition.

Now that we (can) explicitly remove the object from the bus, we can do
that properly, fixing a longstanding bug.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib