During a join of a large DB, processing the linked attributes can take a
long time. The join hangs in 'Committing SAM database' for many minutes
with no indication of whether it's making progress or not.
This patch adds some extra debug to show how far through processing the
linked attributes we are, when there are many thousands of links.
Signed-off-by: Tim Beale <timbeale@catalyst.net.nz> Reviewed-by: Andrew Bartlett <abartlet@samba.org>