Remove $FreeBSD$: one-line sh pattern

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

xo: Disable -Wunused-but-set-variable.

Presumably these warnings will be fixed upstream at some point.

contrib/libxo/xo/xo.c:99:9: error: variable 'hflag' set but not used [-Werror,-Wunused-but-set-variable]
int hflag = 0, jflag = 0, tflag = 0,
^
contrib/libxo/xo/xo.c:99:20: error: variable 'jflag' set but not used [-Werror,-Wunused-but-set-variable]
int hflag = 0, jflag = 0, tflag = 0,
^
contrib/libxo/xo/xo.c:99:31: error: variable 'tflag' set but not used [-Werror,-Wunused-but-set-variable]
int hflag = 0, jflag = 0, tflag = 0,
^
contrib/libxo/xo/xo.c:100:2: error: variable 'zflag' set but not used [-Werror,-Wunused-but-set-variable]
zflag = 0, qflag = 0, star1 = 0, star2 = 0;
^
contrib/libxo/xo/xo.c:100:13: error: variable 'qflag' set but not used [-Werror,-Wunused-but-set-variable]
zflag = 0, qflag = 0, star1 = 0, star2 = 0;
^

Reviewed by: sjg
Differential Revision: https://reviews.freebsd.org/D40668

Allow proper builds of libxo's CSV encoder:
- Move libxo.a build to subdirectory (lib/libxo/libxo/Makefile)
- Add .WAIT target to delay encoder build til after libxo
- Use FILES to install encoder library as csv.enc
- Update import script to put xo_config.h in new location

Add HAS_TESTS to all Makefiles that are currently using the
`SUBDIR.${MK_TESTS}+= tests` idiom.

This is a follow up to r321912.

Convert traditional ${MK_TESTS} conditional idiom for including test
directories to SUBDIR.${MK_TESTS} idiom

This is being done to pave the way for future work (and homogenity) in
^/projects/make-check-sandbox .

No functional change intended.

MFC after: 1 weeks

xo_config.h no longer in contrib, so -I's needed

PR: /homes/sjg/commit-logs/freebsd/libxo/xo_config.diff
Reviewed by: jkim

Make libxo depend on libutil because it uses humanize_number after r287111

Remove overlinking in lib/libxo/tests, sbin/savecore, and
usr.bin/{iscsictl,wc,xo}

PR: 203673
Sponsored by: EMC / Isilon Storage Division

Integrate the tests from libxo into the FreeBSD test suite

The functional_test.sh harness for each test subdir was inspired
by the version in bin/sh/tests/functional_test.sh

Some gymnastics were required to deal with implicit rules for
.c / .o -> .out as the suffix transformation rules were
incorrectly trying to create the test outputs from some of the
source files

Sponsored by: EMC / Isilon Storage Division

Use LIBXOSRC instead of LIBXO when defining the path to contrib/libxo

The latter is already defined in bsd.libnames.mk, so avoid the conflict
in case someone copy-pastes make variables

While here, switch path to the top of the source tree with SRCTOP

Upgrade libxo to 0.4.5.

Local changes incorporated by 0.4.5: r284340
Local changes retained: r276260, r282117

Obtained from: https://github.com/Juniper/libxo

Convert to usr.bin/ to LIBADD
Reduce overlinking

Hook xo(1) to the build -- it's like echo, but uses libxo to
support emitting machine-readable output.

Sponsored by: Juniper Networks, Inc.