After a firts failed attempt, BSD diff is now good enough to replace
GNU diff.

Relnotes:	yes

etcupdate requires --change-group-format it is not easy to implement
in bsd diff so for now readd GNU diff

Some of the modifications from the previous summer of code has been integrated
Modification for compatibility with GNU diff output has been added

Main difference with OpenBSD:
Implement multiple GNU diff options:
* --ignore-file-name-case
* --no-ignore-file-name-case
* --normal
* --tabsize
* --strip-trailing-cr
Make diff -p compatible with GNU diff
Implement diff -l
Make diff -r compatible with GNU diff

Capsicumize diffing 2 regular files
Add a simple test suite

Approved by:	AsiaBSDcon devsummit
Obtained from:	OpenBSD, GSoC
Relnotes:	yes

after r298107

Summary of changes:

- Replace all instances of FILES/TESTS with ${PACKAGE}FILES. This ensures that
  namespacing is kept with FILES appropriately, and that this shouldn't need
  to be repeated if the namespace changes -- only the definition of PACKAGE
  needs to be changed
- Allow PACKAGE to be overridden by callers instead of forcing it to always be
  `tests`. In the event we get to the point where things can be split up
  enough in the base system, it would make more sense to group the tests
  with the blocks they're a part of, e.g. byacc with byacc-tests, etc
- Remove PACKAGE definitions where possible, i.e. where FILES wasn't used
  previously.
- Remove unnecessary TESTSPACKAGE definitions; this has been elided into
  bsd.tests.mk
- Remove unnecessary BINDIRs used previously with ${PACKAGE}FILES;
  ${PACKAGE}FILESDIR is now automatically defined in bsd.test.mk.
- Fix installation of files under data/ subdirectories in lib/libc/tests/hash
  and lib/libc/tests/net/getaddrinfo
- Remove unnecessary .include <bsd.own.mk>s (some opportunistic cleanup)

Document the proposed changes in share/examples/tests/tests/... via examples
so it's clear that ${PACKAGES}FILES is the suggested way forward in terms of
replacing FILES. share/mk/bsd.README didn't seem like the appropriate method
of communicating that info.

MFC after: never probably
X-MFC with: r298107
PR: 209114
Relnotes: yes
Tested with: buildworld, installworld, checkworld; buildworld, packageworld
Sponsored by: EMC / Isilon Storage Division

Sponsored by:	The FreeBSD Foundation

Sponsored by:	EMC / Isilon Storage Division

Sponsored by:	The FreeBSD Foundation

This is not properly respecting WITHOUT or ARCH dependencies in target/.
Doing so requires a massive effort to rework targets/ to do so.  A
better approach will be to either include the SUBDIR Makefiles directly
and map to DIRDEPS or just dynamically lookup the SUBDIR.  These lose
the benefit of having a userland/lib, userland/libexec, etc, though and
results in a massive package.  The current implementation of targets/ is
very unmaintainable.

Currently rescue/rescue and sys/modules are still not connected.

Sponsored by:	EMC / Isilon Storage Division

netbsd-tests.test.mk (r289151)

- Eliminate explicit OBJTOP/SRCTOP setting
- Convert all ad hoc NetBSD test integration over to netbsd-tests.test.mk
- Remove unnecessary TESTSDIR setting
- Use SRCTOP where possible for clarity

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

This has not been needed since r246865 in projects/bmake.

Sponsored by:	EMC / Isilon Storage Division