Fix reference counting bug in virsh console

Fix reference counting bug in virsh console

The event watches need to be removed before the event loop
terminates, otherwise they cause a dangling reference to
be held on the virStreamPtr, which in turns holds a reference
on virConnectPtr, which in turn causes errors like

  "Failed to disconnect from the hypervisor"

* tools/console.c: Remove watches before event loop quits
* tools/virsh.c: Print out dangling reference count