Fix logic inversion.

PR:		docs/174966
Submitted by:	Christian Ullrich <chris+freebsd@chrullrich.net>
Approved by:	bcr (mentor)
Reference something which exists instead of the non-existent runsocks
program.

PR:		docs/173664
Submitted by:	wkoszek
Approved by:	bcr (mentor)
Cleanup the handling of address scopes. Announce in the INIT/INIT-ACK
only the supported address types. While there, do some whitespace
cleanups.

MFC after: 1 week
Add dtc to the build.
Fix breakage introduced in r246318.
Add nmtree to ITOOLS if it is installed on the host instead of keying off
the BOOTSTRAPPING variable.  The previous test was wrong because
BOOTSTRAPPING is 0 in most cases.

Tested by:	db