vbox_snapshot_conf: Resolve Coverity warnings
vbox_snapshot_conf: Resolve Coverity warnings

Clean up some Coverity warnings from commit id '4dc5d8f1'

datto/libvirt,rlaager/libvirt,taget/libvirt,crobinso/libvirt,taget/libvirt,datto/libvirt,jardasgit/libvirt,crobinso/libvirt,rlaager/libvirt,agx/libvirt,nertpinx/libvirt,elmarco/libvirt,zippy2/libvirt,eskultety/libvirt,libvirt/libvirt,jardasgit/libvirt,shugaoye/libvirt,olafhering/libvirt,elmarco/libvirt,eskultety/libvirt,rlaager/libvirt,zippy2/libvirt,andreabolognani/libvirt,crobinso/libvirt,nertpinx/libvirt,VenkatDatta/libvirt,shugaoye/libvirt,jfehlig/libvirt,jardasgit/libvirt,eskultety/libvirt,libvirt/libvirt,elmarco/libvirt,taget/libvirt,eskultety/libvirt,andreabolognani/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,agx/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,nertpinx/libvirt,taget/libvirt,VenkatDatta/libvirt,zippy2/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,datto/libvirt,olafhering/libvirt,elmarco/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,zippy2/libvirt,shugaoye/libvirt,crobinso/libvirt,andreabolognani/libvirt,datto/libvirt,agx/libvirt,libvirt/libvirt,olafhering/libvirt,shugaoye/libvirt,libvirt/libvirt,agx/libvirt,olafhering/libvirt,rlaager/libvirt,fabianfreyer/libvirt,agx/libvirt,VenkatDatta/libvirt,andreabolognani/libvirt,elmarco/libvirt,taget/libvirt,datto/libvirt,nertpinx/libvirt,rlaager/libvirt,nertpinx/libvirt,eskultety/libvirt,andreabolognani/libvirt,jfehlig/libvirt