LU-7845 lnet: check if ni is in current net namespace

LU-7845 lnet: check if ni is in current net namespace

Add new 'ni_net_ns' field to struct lnet_ni to hold a reference
to original net namespace in which ni is created.
In LNetDist(), check if ni was created in same net namespace as
current's one. If not, assign order above 0xffff0000, to make
this ni not a priority.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I5abde6e325983352b42c0eafe16aef22567e3e0e
Reviewed-on: http://review.whamcloud.com/21884
Tested-by: Jenkins
Reviewed-by: Olaf Weber <olaf@sgi.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>