LU-1789 protocol: reserve connect flag for lightweight conn

LU-1789 protocol: reserve connect flag for lightweight conn

Reserve connection flag for lightweight connection support.
Although this feature will never be supported on 2.1, it still avoids
flag conflicts.

Signed-off-by: Johann Lombardi <johann@whamcloud.com>
Change-Id: I1b943579d8c46cce0d70a5df45d35874bf63b29b
Reviewed-on: http://review.whamcloud.com/3853
Tested-by: Hudson
Reviewed-by: Niu Yawei <niu@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>