libcli: Add debug message if fail to negoatiate SMB protocol

libcli: Add debug message if fail to negoatiate SMB protocol

Currently if the client and server can't negotiate an SMB protocol, you
just get the followiing error on the client-side, which doesn't tell you
much.
ERROR(runtime): uncaught exception - (3221225667, 'The network responded
incorrectly.')

This patch adds a debug message to help highlight what's actually going
wrong.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13621

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Sep 28 11:25:29 CEST 2018 on sn-devel-144