qemu: Fix virFileMakePath error handling in snapshot creation
qemu: Fix virFileMakePath error handling in snapshot creation

virFileMakePath returns an errno value on error, that will never
be negative. An virFileMakePath error would have been ignored here,
instead of being reported correctly.

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