[libvirt] [PATCH 1/5]: Shore up virGetLastError handling

While doing testing on this patch series, I mistakenly added a bogus piece of storage XML to libvirtd, which was saved in /etc/libvirt/storage. On subsequent stop/start of libvirtd, because of another bug (fixed in a later patch), an error wasn't being set properly in an error path, so libvirtd was SEGV'ing in storage_conf.c:virStoragePoolObjLoad when trying to dereference the NULL err returned from virGetLastError(). Make this more robust against errors by always doing "err ? err->message : NULL" in the printf. I looked around the tree and found a couple of other places that weren't guarded, so this patch fixes them as well. Signed-off-by: Chris Lalancette <clalance(a)redhat.com&gt;