nodesuspend: report unsupported if systemd & pm-utils aren't available
nodesuspend: report unsupported if systemd & pm-utils aren't available

When libvirtd is run inside a container it is normal that neither
systemd nor pm-utils will be available. In this case there is no way to
suspend the host, so libvirt should just report the feature unsupported
instead of raising an error.

Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

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