MFC r314651,r318439,r318440:

r314651:

sys/modules: normalize .CURDIR-relative paths to SRCTOP

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64

r318439:

Normalize .PATH on SRCTOP

This will help Jenkins dedupe 9 warnings between the static build and
the module build of ipsec(4).

Missed in SRCTOP conversion in r314651.

MFC with: r314651

r318440:

Normalize SYSDIR on SRCTOP instead of .CURDIR

This is being done to simplify pathing for CFLAGS and source files.

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

Clean up a bit of the INET/INET6 mess wrt options.

Let's see if we can fix the NOINET if_gif(4) module build after r276215
going by example.

Automate options INET/INET6 turning into MK_$opt_SUPPORT
correctly. Fixes if_gfe when building without INET6 and
simplifies if_gif's Makefile.

Sponsored by: Netflix, Inc

opt_mrouting.h isn't needed anymore.

MFC after: 1 month

Silence a bmake(1) warning in the gif(4) module build
when built with WITHOUT_INET6.

LGTM: sbruno
Sponsored by: The FreeBSD Foundation

Remove dependence on source tree options. Move all kernel module
options into kern.opts.mk and change all the places where we use
src.opts.mk to pull in the options. Conditionally define SYSDIR and
use SYSDIR/conf/kern.opts.mk instead of a CURDIR path. Replace all
instances of CURDIR/../../etc with STSDIR, but only in the affected
files.

As a special compatibility hack, include bsd.owm.mk at the top of
kern.opts.mk to allow the bare build of sys/modules to work on older
systems. If the defaults ever change between 9.x, 10.x and current for
these options, however, you'll wind up with the host OS' defaults
rather than the -current defaults. This hack will be removed when
we no longer need to support this build scenario.

Reviewed by: jhb
Differential Revision: https://phabric.freebsd.org/D529

Revert the logic change from r269540. If the opt_inet6.h file is empty
we set MK_INET6_SUPPORT to no, not if we do define INET6.
This way we do not try to build IPv6 parts in if the kernel doesn't support
them.

This unbreaks several kernel configurations building modules but no INET6.

Move most of the 15 variations on generating opt_inet.h and
opt_inet6.h into kmod.mk by forcing almost everybody to eat the same
dogfood. While at it, consolidate the opt_bpf.h and opt_mroute.h
targets here too.

Use src.opts.mk in preference to bsd.own.mk except where we need stuff
from the latter.

Remove opt_mac.h generation for various kernel modules that no longer
require it.

Submitted by: pjd

Reimplementation of world/kernel build options. For details, see:

http://lists.freebsd.org/pipermail/freebsd-current/2006-March/061725.html

The src.conf(5) manpage is to follow in a few days.

Brought to you by: imp, jhb, kris, phk, ru (all bugs are mine)

When compiling with the kernel, detect if INET6 support should be disabled.

In this case, disable wrapping of fake opt_*.h targets in
"if defined(KERNBUILDDIR)" for now since the new way of
building modules with the kernel can't handle dynamic SRCS
depending on build options yet.

Let modules use the kernel's opt_*.h files if built along with
the kernel by wrapping all targets for fake opt_*.h files in
.if defined(KERNBUILDDIR). Thus, such fake files won't be
created at all if modules are built with the kernel.

Some modules undergo cleanup like removing unused or unneeded
options or .h files, without which they wouldn't build this way
or the other.

Reviewed by: ru
Tested by: no binary changes in modules built alone
Tested on: i386 sparc64 amd64

NOINET6 -> NO_INET6

kmod.mk knows how to create empty opt_*.h files so let it deal with the
NOINET6 case.

Reported by: ru

Allow the gif module to be built without IPv6 support when NOINET6 is
defined.

Submitted by: mitrohin a.s. <swp at uni-altai dot ru>

Depend on opt_mac.h.

Drop <bsd.man.mk> support from <bsd.kmod.mk>.

Not objected to by: -current

gif(4) and stf(4) modernization:

- Remove gif dependencies from stf.
- Make gif and stf into modules
- Make gif cloneable.

PR: kern/27983
Reviewed by: ru, ume
Obtained from: NetBSD
MFC after: 1 week