r24589: Refactor our vuid code so that we keep the same

r24589: Refactor our vuid code so that we keep the same
vuid that was allocated whilst the connection is
being constructed and after the connection has been set up.
This is what Windows does and at least one client
(and HP printer) depends on this behaviour. As it
depends on the req struct not yet ported to SAMBA_3_2_0
(Volker, hint hint.... :-) I am not yet adding this
to that branch, but will investigate that tomorrow.
Jeremy.
(This used to be commit a54f2805df92c67e74a6764568eedebe394fd500)