qemu: support setting vlan tag for <interface type='hostdev'>
qemu: support setting vlan tag for <interface type='hostdev'>

The underlying function to set the vlan tag of an SR-IOV network
device was already in place (although an extra patch to save/restore
the original vlan tag was needed), and recent patches added the
ability to configure a vlan tag. This patch just ties those two
together.

An SR-IOV device doesn't support vlan trunking, so if anyone tries to
configure more than a single tag, or set the trunk flag, and error is
logged.

jardasgit/libvirt,jeckersb/libvirt,taget/libvirt,cbosdo/libvirt,warewolf/libvirt,siboulet/libvirt-openvz,elmarco/libvirt,agx/libvirt,zhlcindy/libvirt-1.1.4-maintain,nertpinx/libvirt,trainstack/libvirt,libvirt/libvirt,wiedi/libvirt,siboulet/libvirt-openvz,elmarco/libvirt,libvirt/libvirt,bjzhang/libvirt,rlaager/libvirt,VenkatDatta/libvirt,andreabolognani/libvirt,wiedi/libvirt,novel/fbsd-libvirt,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,bjzhang/libvirt,warewolf/libvirt,bjzhang/libvirt,shugaoye/libvirt,warewolf/libvirt,nertpinx/libvirt,shugaoye/libvirt,trainstack/libvirt,datto/libvirt,jeckersb/libvirt,zhlcindy/libvirt-1.1.4-maintain,iam-TJ/libvirt,andreabolognani/libvirt,crobinso/libvirt,jardasgit/libvirt,cbosdo/libvirt,andreabolognani/libvirt,novel/fbsd-libvirt,fabianfreyer/libvirt,rlaager/libvirt,warewolf/libvirt,iam-TJ/libvirt,datto/libvirt,taget/libvirt,jardasgit/libvirt,nertpinx/libvirt,warewolf/libvirt,jeckersb/libvirt,trainstack/libvirt,datto/libvirt,olafhering/libvirt,eskultety/libvirt,andreabolognani/libvirt,wiedi/libvirt,emaste/libvirt,trainstack/libvirt,emaste/libvirt,olafhering/libvirt,fabianfreyer/libvirt,zippy2/libvirt,wiedi/libvirt,olafhering/libvirt,crobinso/libvirt,taget/libvirt,zippy2/libvirt,iam-TJ/libvirt,jeckersb/libvirt,VenkatDatta/libvirt,elmarco/libvirt,novel/fbsd-libvirt,trainstack/libvirt,crobinso/libvirt,VenkatDatta/libvirt,libvirt/libvirt,emaste/libvirt,andreabolognani/libvirt,cbosdo/libvirt,zippy2/libvirt,novel/fbsd-libvirt,VenkatDatta/libvirt,emaste/libvirt,VenkatDatta/libvirt,taget/libvirt,fabianfreyer/libvirt,zhlcindy/libvirt-1.1.4-maintain,datto/libvirt,rlaager/libvirt,nertpinx/libvirt,bjzhang/libvirt,agx/libvirt,iam-TJ/libvirt,warewolf/libvirt,eskultety/libvirt,wiedi/libvirt,siboulet/libvirt-openvz,elmarco/libvirt,novel/fbsd-libvirt,novel/fbsd-libvirt,cbosdo/libvirt,iam-TJ/libvirt,datto/libvirt,novel/fbsd-libvirt,emaste/libvirt,jeckersb/libvirt,eskultety/libvirt,novel/fbsd-libvirt,jeckersb/libvirt,zippy2/libvirt,libvirt/libvirt,emaste/libvirt,jardasgit/libvirt,shugaoye/libvirt,bjzhang/libvirt,olafhering/libvirt,shugaoye/libvirt,agx/libvirt,nertpinx/libvirt,warewolf/libvirt,eskultety/libvirt,wiedi/libvirt,eskultety/libvirt,shugaoye/libvirt,zhlcindy/libvirt-1.1.4-maintain,crobinso/libvirt,agx/libvirt,rlaager/libvirt,jfehlig/libvirt,wiedi/libvirt,elmarco/libvirt,trainstack/libvirt,iam-TJ/libvirt,taget/libvirt,fabianfreyer/libvirt,cbosdo/libvirt,fabianfreyer/libvirt,siboulet/libvirt-openvz,jfehlig/libvirt,siboulet/libvirt-openvz,jfehlig/libvirt,iam-TJ/libvirt,jardasgit/libvirt,jfehlig/libvirt,novel/fbsd-libvirt,jeckersb/libvirt,agx/libvirt,trainstack/libvirt,emaste/libvirt