finally got sick of the "extern int Client" code and the stupid

finally got sick of the "extern int Client" code and the stupid
assumption that we have one socket everywhere

while doing so I discovered a few bugs!

1) the clientgen session retarget code if used from smbd or nmbd would
cause a crash as it called close_sockets() which closed our main
socket! fixed by removing close_sockets() completely - it is unnecessary

2) the caching in client_addr() and client_name() was bogus - it could
easily get fooled and give the wrong result. fixed.

3) the retarget could could recurse, allowing an easy denial of
service attack on nmbd. fixed.