use virStorageFileIsSharedFS utility function in qemudDomainSaveFlag
use virStorageFileIsSharedFS utility function in qemudDomainSaveFlag

Previously, this function had it's own bit of code performing the same
function. Since there's now an equivalent utility function, let's use it.

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