qemu: snapshot: Remove memory image if external checkpoint fails
qemu: snapshot: Remove memory image if external checkpoint fails

When the disk snapshot part of an external system checkpoint fails the
memory image is retained. This patch adds code to remove the image in
such case.

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