netnsid_getifaddrs: fix check for netnsid support
netnsid_getifaddrs: fix check for netnsid support

The loopback device needs to be up for netnsid_getifaddrs() to actually
work. Let's avoid this churn and be smarter and assign a netnsid to the
host as seen from another network namespace.
Also, log an error on failure.

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>

stgraber/lxd,lxc/lxd,stgraber/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,mjeanson/lxd,hallyn/lxd,stgraber/lxd,Skarlso/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,atxwebs/lxd,atxwebs/lxd,lxc/lxd,Skarlso/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,Skarlso/lxd,Skarlso/lxd,mjeanson/lxd,atxwebs/lxd,mjeanson/lxd