[libvirt] [PATCH v2 1/4] Add virDomainSendProcessSignal API

[Eric Blake]

> > Drop this hunk (rather, move it to patch 4/4).  Such a check
> > should be done in the hypervisor driver, not in the entry
> > point.  Otherwise, if we add a new signal later, this hunk
> > would prevent an older virsh from sending the new signal.
> 
> On the other hand, you _should_ add a check here that prevents
> signum==0, since we have documented that signum must be non-zero
> as part of the API contract.

Arg. Can't type.  signum==0 is valid, pid_value==0 is the forbidden
item.