source3: initilize_password_db after a fork.

source3: initilize_password_db after a fork.

This is required because we need a new pointer for LDB after the fork,
and with LMDB we can not longer rely on tdb_reopen_all() to do that
for us.

This can not be done in reinit_after_fork() due to the dependency loop
this would create.

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>