MFC r314654:

cddl: normalize paths using SRCTOP-relative paths or :H when possible

This simplifies make logic/output

While here, remove bogus CFLAGS which look for headers in cddl/lib/libumem.
There aren't any source files there (just Makefiles)

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

Simplify the LIBRARIES_ONLY hacks so that install: is not needed here.

This uses the same pattern that I applied to the other cases of this in
the csu directories.

Sponsored by: EMC / Isilon Storage Division

Add META_MODE support.

Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.

Still need to add real targets under targets/ to build packages.

Differential Revision: D2796
Reviewed by: brooks imp

Work around the implementation of LIBRARIES_ONLY. It causes drti.o to
not be installed in /usr/lib32 on systems with compat-32 support.

This fix has two parts. First, the build is forced by linking drti.o
into a dummy internal library. Second, the object file is installed
manually in the LIBRARIES_ONLY case.

MFC after: 3 days

Change the Makefile in cddl/lib/drti to use bsd.lib.mk instead of
bsd.prog.mk -- we need to compile PIC, which requires a library build.
With this change, USDT (userspace DTrace probes) work from within
shared libraries.

PR: kern/159046
Submitted by: Alex Samorukov <samm at os2.kiev.ua>
Comments by: Scott Lystig Fritchie <slfritchie at snookles.com>
MFC after: 3 days

Use ${PICFLAG} instead of -fpic.

Don't link drti.o with libelf_pic.a. This means that all software with
userland SDT probes must be linked with libelf explicitly.

Requested by: kib
Sponsored by: The FreeBSD Foundation

Link drti.o with a PIC version of libelf. This is needed because
drti.o depends on libelf and this avoids linking every other drti.o
program (namely programs with USDT probes) with libelf.

Sponsored by: The FreeBSD Foundation

Remove manual .includes in cddl Makefiles

- Break the dependency on ../Makefile.inc for .PATH, and include
../Makefile.inc implicitly. This is required to ...
- Set WARNS?=6 in top-level Makefile.inc
- Remove now redundant WARNS settings, add WARNS?=0 where appropriate
- Remove redundant SHLIB_MAJOR overrides
- Use NO_MAN, not MK_MAN=no
- Remove redundant inclusion of bsd.own.mk
- Order Makefiles more according to style.Makefile(9)
- Reduce diff of cddl Makefiles against each other

No objection: pjd
Approved by: ed (co-mentor)

Add the DTrace libraries and D library scripts.