conf: Fix declaration of virNetworkDNS(Hosts)Def struct
conf: Fix declaration of virNetworkDNS(Hosts)Def struct

The struct A {} A; construct triggers a linker error on OSX about
duplicate symbols. This also differs from the common struct style.

Switch to common style to fix this.

Reported by Justin Clift.

libvirt/libvirt,leilihh/libvirt,soulxu/libvirt-xuhj,kantai/libvirt-vfork,zippy2/libvirt,foomango/libvirt,novel/fbsd-libvirt,elmarco/libvirt,agx/libvirt,jfehlig/libvirt,zippy2/libvirt,rlaager/libvirt,warewolf/libvirt,bjzhang/libvirt,usc-isi/libvirt,rmarwaha/libvirt,novel/fbsd-libvirt,olafhering/libvirt,usc-isi/libvirt,jfehlig/libvirt,datto/libvirt,nertpinx/libvirt,andreabolognani/libvirt,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,iam-TJ/libvirt,danwent/libvirt-ovs,datto/libvirt,VenkatDatta/libvirt,siboulet/libvirt-openvz,trainstack/libvirt,dumbbell/libvirt,cbosdo/libvirt,taget/libvirt,soulxu/libvirt-xuhj,danwent/libvirt-ovs,bjzhang/libvirt,libvirt/libvirt,emaste/libvirt,emaste/libvirt,agx/libvirt,VenkatDatta/libvirt,shugaoye/libvirt,usc-isi/libvirt,emaste/libvirt,zhlcindy/libvirt-1.1.4-maintain,foomango/libvirt,datto/libvirt,kantai/libvirt-vfork,novel/fbsd-libvirt,jeckersb/libvirt,eskultety/libvirt,rlaager/libvirt,eskultety/libvirt,nertpinx/libvirt,rmarwaha/libvirt,wiedi/libvirt,warewolf/libvirt,wiedi/libvirt,danwent/libvirt-ovs,wiedi/libvirt,rlaager/libvirt,shugaoye/libvirt,danwent/libvirt-ovs,shugaoye/libvirt,agx/libvirt,jfehlig/libvirt,warewolf/libvirt,dumbbell/libvirt,cbosdo/libvirt,novel/fbsd-libvirt,trainstack/libvirt,VenkatDatta/libvirt,datto/libvirt,leilihh/libvirt,emaste/libvirt,agx/libvirt,crobinso/libvirt,trainstack/libvirt,andreabolognani/libvirt,rmarwaha/libvirt1,warewolf/libvirt,fabianfreyer/libvirt,jeckersb/libvirt,novel/fbsd-libvirt,crobinso/libvirt,jardasgit/libvirt,wiedi/libvirt,leilihh/libvirt,crobinso/libvirt,dumbbell/libvirt,rmarwaha/libvirt1,novel/fbsd-libvirt,elmarco/libvirt,warewolf/libvirt,rmarwaha/libvirt,rmarwaha/libvirt,novel/fbsd-libvirt,datto/libvirt,jeckersb/libvirt,wiedi/libvirt,soulxu/libvirt-xuhj,emaste/libvirt,andreabolognani/libvirt,olafhering/libvirt,usc-isi/libvirt,dumbbell/libvirt,foomango/libvirt,nertpinx/libvirt,wiedi/libvirt,usc-isi/libvirt,cbosdo/libvirt,VenkatDatta/libvirt,taget/libvirt,rmarwaha/libvirt,rmarwaha/libvirt1,zhlcindy/libvirt-1.1.4-maintain,novel/fbsd-libvirt,kantai/libvirt-vfork,emaste/libvirt,siboulet/libvirt-openvz,rmarwaha/libvirt,jfehlig/libvirt,foomango/libvirt,leilihh/libvirt,eskultety/libvirt,warewolf/libvirt,fabianfreyer/libvirt,iam-TJ/libvirt,foomango/libvirt,trainstack/libvirt,olafhering/libvirt,iam-TJ/libvirt,dumbbell/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,kantai/libvirt-vfork,trainstack/libvirt,rlaager/libvirt,jardasgit/libvirt,nertpinx/libvirt,zippy2/libvirt,zhlcindy/libvirt-1.1.4-maintain,shugaoye/libvirt,VenkatDatta/libvirt,novel/fbsd-libvirt,jardasgit/libvirt,emaste/libvirt,elmarco/libvirt,shugaoye/libvirt,trainstack/libvirt,zippy2/libvirt,crobinso/libvirt,iam-TJ/libvirt,libvirt/libvirt,eskultety/libvirt,leilihh/libvirt,trainstack/libvirt,fabianfreyer/libvirt,siboulet/libvirt-openvz,cbosdo/libvirt,rmarwaha/libvirt1,rmarwaha/libvirt1,jeckersb/libvirt,elmarco/libvirt,kantai/libvirt-vfork,zhlcindy/libvirt-1.1.4-maintain,iam-TJ/libvirt,wiedi/libvirt,bjzhang/libvirt,jeckersb/libvirt,jeckersb/libvirt,andreabolognani/libvirt,soulxu/libvirt-xuhj,soulxu/libvirt-xuhj,fabianfreyer/libvirt,elmarco/libvirt,agx/libvirt,leilihh/libvirt,bjzhang/libvirt,olafhering/libvirt,taget/libvirt,taget/libvirt,andreabolognani/libvirt,siboulet/libvirt-openvz,iam-TJ/libvirt,iam-TJ/libvirt,eskultety/libvirt,jeckersb/libvirt,libvirt/libvirt,siboulet/libvirt-openvz,rmarwaha/libvirt1,danwent/libvirt-ovs,bjzhang/libvirt,nertpinx/libvirt,dumbbell/libvirt,warewolf/libvirt,taget/libvirt,jardasgit/libvirt,cbosdo/libvirt