Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Remove more quotes around Makefile .error/.warn/.info strings.

Reviewed by: imp, emaste
Differential Revision: https://reviews.freebsd.org/D34175

Fix LDADD/DPADD that should be LIBADD.

Sponsored by: EMC / Isilon Storage Division

Standardize on OBJTOP in and outside of META MODE.

Sponsored by: EMC / Isilon Storage Division

Simplify netbsd-tests.test.mk

- projects/bmake and subsequent commits provide SRCTOP; there's no need to
manually specify it now.
- Compute a sane default for OBJTOP based on .OBJDIR and RELDIR. Manually
specifying this is probably no longer needed, but it persists just in case
(supporting commits will need to be made to move it out of some of the meta
.mk files).
- Compute a sane default for TESTSRC. Error out if the path cannot be found.

MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division

Import proper fix for misc/49356 (/usr/include/atf-c/config.h) after atf-c/config.h
was removed from the build

Pointyhat to: me (again, for not running make delete-old after running test builds)

Add Makefile snippet to ease porting NetBSD testcases to FreeBSD from
contrib/netbsd-tests

This Makefile snippet handles polluting testcases with -lnetbsd, specific
headers for ATF version differences, and does necessary rewriting for the
testcases to match the format discussed on the TestSuite wiki page
(t_<foo> -> <foo>_test)

One must define SRCTOP (inspired by projects/bmake), OBJTOP, and TESTSRC
(e.g. contrib/netbsd-tests/lib/libc/gen) to use the Makefile snippet

Test programs are specific either via NETBSD_ATF_TESTS_C or NETBSD_ATF_TESTS_SH

C++ analogs aren't currently implemented.

The imported testcases will be cleaned up to use this Makefile snippet pseudo
"API".