lib: Avoid looking at fcntl'ed gencache.tdb

lib: Avoid looking at fcntl'ed gencache.tdb

gencache_notrans.tdb is much cheaper to look at than gencache.tdb because it's
mutexed and thus avoids expensive fcntl locks. This patch aggressively uses the
shared _notrans tdb for both positive and negative entries. It's a replacement
for the memcache copy in every process that was removed a few patches ago.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>