Fix leak of objects when reconnecting to QEMU instances

Fix leak of objects when reconnecting to QEMU instances

The 'error' cleanup block in qemuProcessReconnect() had a
'return' statement in the middle of it. This caused a leak
of virConnectPtr & virQEMUDriverConfigPtr instances. This
was identified because netcf recently started checking its
refcount in libvirtd shutdown:

netcfStateCleanup:109 : internal error: Attempt to close netcf state driver with open connections

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>