signals: backtrace some more exotic fatal signals
signals: backtrace some more exotic fatal signals

We're not likely to see these, but if we do, we want it in the logs!

Signed-off-by: Colin McCabe <c0eabe2887ac1e91c280795b9fca010e21066283@hq.newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph