MFC r313653:

Use SRCTOP instead of .CURDIR relative paths with ".."

This simplifies pathing in make/displayed output

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Build usr.bin/ with WARNS=6 by default.

Also add some missing $FreeBSD$ to keep svn happy.

Fix build in the !NOATM case by using the begemot library in place of
using libisc which was a part of BIND8.

Discussed with: des, re, dougb
Submitted by: harti (one part)
Reviewed by: harti (previous version)

Fixed style of DPADD and LDADD assignments as per style.Makefile(5).

Build the NgATM user space SSCOP tool (unless NOATM is defined).