selftest: Print link meta-data when developer debugging is used

selftest: Print link meta-data when developer debugging is used

For Windows, DRS is the only way to see the RMD_VERSION of a link, or to
tell what inactive links the DC. Add some debug to display this
information. By default, this debug is turned off.

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Oct 20 08:01:35 CEST 2017 on sn-devel-144