Merge nvi-2.1.1 -> 2.1.2
Consistently add the relocation offset only when the ELF type is not
ET_EXEC. This fixes several problems with the DTrace pid provider not
being able to match probes.

Reviewed by:	rpaulo
MFC after:	2 weeks
Add a brief comment about VM_GUEST and vm_guest_sysctl_names relationship.

Suggested by:	Roger Pau Monne
Reviewed by:	Roger Pau Monne