qemu: Resolve Coverity UNINIT
qemu: Resolve Coverity UNINIT

Coverity complained that 'vm' wasn't initialized before jumping to
cleanup: and calling virDomainObjEndAPI if the VIR_STRDUP fails.
So I initialized vm = NULL and also moved the VIR_STRDUP closer to
usage and used endjob for goto. Lots of other reasons for failures.

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