Get it builing on OpenBSD 5.3

Turns out 4.8 and 5.3 offer mutually incompatible kvm_getprocs
interfaces. kvm_getproc2 was removed at some point, and kvm_getprocs
changed to have the API that kvm_getproc2 used to have.

I've decided to sac 4.8 support. devio.us still runs 4.8, but their
ulimit is set too low for vere anyway.

This reverts commit b9a83028891652e2e994f7c0a1cbb992c647f145.