MFC r313653:

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

This simplifies pathing in make/displayed output

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Add META_MODE support.

Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.

Still need to add real targets under targets/ to build packages.

Differential Revision: D2796
Reviewed by: brooks imp

Convert to usr.bin/ to LIBADD
Reduce overlinking

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).