Add local copy of libnv from FreeBSD.

As of r266830 in FreeBSD current, subdir lib/libnv.
Set up initial non-FreeBSD build of libnv
Add initial Debian packaging for libnv
Rename libcapsicum to libcaprights

This frees up the name libcapsicum to hold the same functionality
as FreeBSD's libcapsicum; FreeBSD puts the functionality of this
library into its libc.
Add local copy of libcapsicum from FreeBSD

As of r266830 in FreeBSD current, subdir lib/libcapsicum.
Set up initial non-FreeBSD build of libcapsicum
Fix libnv exported headers
Add initial Debian packaging for libcapsicum
Add local copy of libcasper from FreeBSD

As of r266830 in FreeBSD current, subdir lib/libcasper.
Set up initial non-FreeBSD build of libcasper
Add initial Debian packaging for libcasper
Fix typo in github url
Add local copy of casper from FreeBSD

As of r266830 in FreeBSD current, subdir libexec/casper.
Add local copy of casperd from FreeBSD

As of r266830 in FreeBSD current, subdir sbin/casperd.
Split out a separate <sys/procdesc.h>
Move all Casper-related code into single casper/ subdir
Add local copy of libpjdlog from FreeBSD

As of r266830 in FreeBSD current, subdir lib/libpjdlog.
Set up initial non-FreeBSD build of libpjdlog
First pass at getting casperd building in Linux

Pulls in pidfile.c from FreeBSD libs/libutil
Fix incorrect macro capitalization