util: Resolve resource leak
util: Resolve resource leak

Need to free @groups in the parent on success similar to other
APIs (virFile*) which use virGetGroupList and virFork.

Reported by Coverity.

jardasgit/libvirt,fabianfreyer/libvirt,eskultety/libvirt,libvirt/libvirt,nertpinx/libvirt,jfehlig/libvirt,olafhering/libvirt,libvirt/libvirt,andreabolognani/libvirt,olafhering/libvirt,jardasgit/libvirt,zippy2/libvirt,nertpinx/libvirt,eskultety/libvirt,olafhering/libvirt,andreabolognani/libvirt,crobinso/libvirt,eskultety/libvirt,fabianfreyer/libvirt,eskultety/libvirt,crobinso/libvirt,andreabolognani/libvirt,jardasgit/libvirt,nertpinx/libvirt,jardasgit/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,zippy2/libvirt,jfehlig/libvirt,eskultety/libvirt,jfehlig/libvirt,libvirt/libvirt,olafhering/libvirt,crobinso/libvirt,andreabolognani/libvirt,zippy2/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,libvirt/libvirt,crobinso/libvirt,zippy2/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt