sys: Remove $FreeBSD$: one-line sh pattern

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

sys: Retire OPENZFS_CWARNFLAGS now that it is empty.

Reviewed by: markj, emaste
Differential Revision: https://reviews.freebsd.org/D39217

openzfs: fix gcc kernel module builds

- Suppress -Wredundant-decls. Ultimately this warning is harmless in
any case, and it does not look like there is a simple way to avoid
redundant declarations in this case without a lot of header pollution
(e.g. having openzfs's shim param.h pulling in sys/kernel.h for hz).
- Suppress -Wnested-externs, which is useless anyway.

Unfortunately it was not sufficient just to modify OPENZFS_CFLAGS,
because the warning suppressions need to appear on the command line
after they are explicitly enabled by CWARNFLAGS from sys/conf/kern.mk,
but OPENZFS_CFLAGS get added before due to use of -I for the shims.

Reviewed by: markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D27685

Merge OpenZFS support in to HEAD.

The primary benefit is maintaining a completely shared
code base with the community allowing FreeBSD to receive
new features sooner and with less effort.

I would advise against doing 'zpool upgrade'
or creating indispensable pools using new
features until this change has had a month+
to soak.

Work on merging FreeBSD support in to what was
at the time "ZFS on Linux" began in August 2018.
I first publicly proposed transitioning FreeBSD
to (new) OpenZFS on December 18th, 2018. FreeBSD
support in OpenZFS was finally completed in December
2019. A CFT for downstreaming OpenZFS support in
to FreeBSD was first issued on July 8th. All issues
that were reported have been addressed or, for
a couple of less critical matters there are
pull requests in progress with OpenZFS. iXsystems
has tested and dogfooded extensively internally.
The TrueNAS 12 release is based on OpenZFS with
some additional features that have not yet made
it upstream.

Improvements include:
project quotas, encrypted datasets,
allocation classes, vectorized raidz,
vectorized checksums, various command line
improvements, zstd compression.

Thanks to those who have helped along the way:
Ryan Moeller, Allan Jude, Zack Welch, and many
others.

Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D25872

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

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64
MFC after: 1 month
Sponsored by: Dell EMC Isilon

Factor out the common code for function boundary tracing instead of
duplicating the entire implementation for both x86 and powerpc. This makes
it easier to add support for other architectures and has no functional
impact.

Phabric: D613
Reviewed by: gnn, jhibbits, rpaulo
Tested by: jhibbits (powerpc)
MFC after: 2 weeks

Use SYSDIR to reference to the top of the sys hierarchy. Define SYSDIR
relative to .CURDIR if not already defined. This makes the makefiles
more readable but also more re-usable and adaptable.

Obtained from: Juniper Networks, Inc.

opensolaris code: translate INVARIANTS to DEBUG and ZFS_DEBUG

Do this by forcing inclusion of
sys/cddl/compat/opensolaris/sys/debug_compat.h
via -include option into all source files from OpenSolaris.
Note that this -include option must always be after -include opt_global.h.

Additionally, remove forced definition of DEBUG for some modules and fix
their build without DEBUG.

Also, meaning of DEBUG was overloaded to enable WITNESS support for some
OpenSolaris (primarily ZFS) locks. Now this overloading is removed and
that use of DEBUG is replaced with a new option OPENSOLARIS_WITNESS.

MFC after: 17 days

Fix the powerpc64 build. MACHINE_CPUARCH is common for powerpc/powerpc64,
not MACHINE_ARCH.

Add FBT for PowerPC DTrace. Also, clean up the DTrace assembly code,
much of which is not necessary for PowerPC.

The FBT module can likely be factored into 3 separate files: common,
intel, and powerpc, rather than duplicating most of the code between
the x86 and PowerPC flavors.

All DTrace modules for PowerPC will be MFC'd together once Fasttrap is
completed.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

- Import the HEAD csup code which is the basis for the cvsmode work.

Add the DTrace kernel module makefiles.