Log Message:
Reinstate the "processes" plugin for NetBSD by initializing the
two per-process context switch counters to -1, indicating no support.
Our kinfo_lwp structure doesn't contain the context switch counters,
which in the kernel is part of the lwp structure.

Also make this build on netbsd-6 and on ports which don't yet have
nearbyint() by simply defining it as rint() on NetBSD.

Bump PKGREVISION.