Fix GetNameServerAsCIDR
Fix GetNameServerAsCIDR

- the function is broken as it does not strip the
  zone id from an IPv6 nameserver address, and it
  returns the IPv6 address with /32

Signed-off-by: Alessandro Boch <5bd2eb5b6f60921d9a2b9cb6a0a86bb947f3d361@docker.com>

docker/docker,cpuguy83/docker,konstruktoid/docker-upstream,moul/docker,gnailuy/docker,docker/docker,nawawi/docker,mahak/docker,paralin/docker,yosifkit/docker,gnailuy/docker,AkihiroSuda/docker,Mokolea/docker,jimjag/docker,mahak/docker,bearstech/moby,trebonian/docker,vdemeester/docker,flavio/docker,flavio/docker,jthelin/docker,nalind/docker,nawawi/docker,thaJeztah/docker,Mokolea/docker,moby/moby,konstruktoid/docker-upstream,trebonian/docker,Mokolea/docker,cpuguy83/docker,Ramzec/docker,djs55/docker,konstruktoid/docker-upstream,moby/moby,cpuguy83/docker,AkihiroSuda/docker,thaJeztah/docker,AkihiroSuda/docker,Ramzec/docker,moul/docker,djs55/docker,AkihiroSuda/docker,moby/moby,trebonian/docker,paralin/docker,yosifkit/docker,Mokolea/docker,nalind/docker,docker/docker,nawawi/docker,djs55/docker,gnailuy/docker,bearstech/moby,paralin/docker,cpuguy83/docker,thaJeztah/docker,jimjag/docker,jameszhan/docker,nalind/docker,jameszhan/docker,trebonian/docker,jimjag/docker,Ramzec/docker,konstruktoid/docker-upstream,moul/docker,flavio/docker,jthelin/docker,flavio/docker,jimjag/docker,mahak/docker,thaJeztah/docker,gnailuy/docker,vdemeester/docker,bearstech/moby,yosifkit/docker,moul/docker,bearstech/moby,nawawi/docker,yosifkit/docker,paralin/docker,vdemeester/docker,nalind/docker,moby/moby,jameszhan/docker,mahak/docker,Ramzec/docker