Add sys.dirdeps.mk to share/mk FILES

A few recent makefiles should have been added to FILES.
Rename sys.machine.mk to local.sys.machine.mk as it is very
tree specific so does not belong in /usr/share/mk/

Reviewed by: stevek
Differential Revision: https://reviews.freebsd.org/D41642

Remove $FreeBSD$: one-line sh pattern

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

Move MACHINE/MACHINE_ARCH handling to sys.machine.mk

Rather than define the TARGETS and TARGET_ARCHES in src/Makefile
put them in sys.machine.mk so they can also be leveraged by
non-top-level builds.

We have TARGET_MACHINE_LIST as the list of MACHINES we build for.

For each MACHINE we have a MACHINE_ARCH_LIST_${MACHINE}
and the first entry of each list is used as default for
MACHINE_ARCH_${MACHINE}

We can now remove a bunch of MACHINE_ARCH.* handling from
local.sys.dirdeps*mk

Reviewed by: imp
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D40083

Move DIRDEPS_BUILD settings to sys.dirdeps.mk

When originally implemented, there was no distinction between
DIRDEPS_BUILD and META_MODE, they were one and the same.

META_MODE however is useful by itself, but since meta.sys.mk
had lots of settings related to DIRDEPS_BUILD its use was limited
to DIRDEPS_BUILD.

Move (most) DIRDEPS_BUILD related items to sys.dirdeps.mk
so that meta.sys.mk can be used for just META_MODE.
There is of course some bluring of the lines, so settings remain
in meta.sys.mk

Add MK_META_ERROR_TARGET to enable the META_MODE .ERROR target
independent of DIRDEPS_BUILD, it copies failed .meta files to ${SB}/error
to make it easier to identify the cause of build failures.

Since sys.dirdeps.mk should be included first, most of
local.meta.sys.mk becomes local.sys.dirdeps.mk
and some other bits need to move to local.sys.dirdeps.env.mk

Also fix dirdeps.mk to not add CURDIR to DIRDEPS when it is SRCTOP.

Reviewed by: bdrewery
Differential Revision: https://reviews.freebsd.org/D40053

Extract some of local.meta.sys.mk to local.meta.sys.env.mk

Latest meta.sys.mk follows sys.mk in including local.meta.sys.env.mk
and local.meta.sys.mk late, but we have things we need done early
so move them to local.meta.sys.env.mk

Update meta.sys.mk and related local*mk

Move the setting of TARGET_SPEC_VARS to local.sys.env.mk
so meta.sys.mk can do the processing, and include local.meta.sys.mk
later.

Move the setting of GENDIRDEPS_FILTER*_VARS from local.gendirdeps.mk
to local.meta.sys.mk so we can automatically set DEP_* at level 1+
to avoid syntax errors when DEP_* variables are used in conditionals
in Makefile.depend files.

Update gendirdeps.mk just to get the documentation about the above.
No functional change.

local.dirdeps.mk be more careful about adding to DIRDEPS to avoid
unnecessary overhead, and introducing cycles in the graph.
Also set DEP_MACHINE_CPUARCH.

Reviewed by: stevek
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D39737

Allow site.*.mk to augment local.*.mk and src.*.mk

Add some extra customization points so that FreeBSD build
can be adapted to local requirements.
We use these to minimize changes to share/mk

Reviewed by: stevek
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D37617

AUTO_OBJ: Hide 'creating dirs' output with 'make -s'.

Reported by: garga
Sponsored by: Dell EMC Isilon

AUTO_OBJ: auto.obj.mk mkdir -p simplification

Sponsored by: Dell EMC Isilon

Move include of make.conf back to its old position.

This means moving include of local.sys.mk and src.sys.mk too.
Introduce new includes to take the early slot, for the purpose
of being able to influence toolchains and the like.

Differential Revision: D2860
Reviewed by: imp