Progress on CR 601

Progress on CR 601

cache the printer_info_2 with the open printer handle.
cache is invalidated on a mod_a_printer() call **on that smbd**.

Yes, this means that the window for admins to step on each other
from different clients just got larger, but since handles a generally
short lived this is probably ok.
(This used to be commit 33c7b7522504fb15989f32add8e9a087c8d9d0fa)