libcli/auth: try to use the current timestamp creds->sequence

libcli/auth: try to use the current timestamp creds->sequence

If the last usage of netlogon_creds_client_authenticator()
is in the past try to use the current timestamp and increment
more than just 2.

If we use netlogon_creds_client_authenticator() a lot within a
second, we increment keep incrementing by 2.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Tue Dec 24 13:18:18 CET 2013 on sn-devel-104