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

While there, remove .Tn from man pages.

Also remove an obsolete comment about the 80386.

MFC after:	1 week
Sponsored by:	Klara, Inc.
Reviewed by:	kevans, allanjude
Differential Revision:	https://reviews.freebsd.org/D38373

Summary:
This knob can be used to make buildsystem prefer generic C implentations of
various functions, instead of machine-specific assembler ones.

Test Plan: `make buildworld` on amd64

Reviewed by: imp, emaste

Differential Revision: https://reviews.freebsd.org/D36076

MFC after:	3 days

As with sha256 add support for accelerated sha512 support to libmd on
arm64. This depends on clang 13+ to build as this is the first release
with the needed intrinsics. Gcc should also support them, however from
a currently unknown release.

Reviewed by:	cem
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33373

This is now unneeded as arm64 can now resolve ifuncs in static binaries

This reverts commit c81ea895b563c4d1e39468a8525284b7474fe850.

Sponsored by:	The FreeBSD Foundation

We don't have ifunc support in static arm64 binaries. Until we do
disable the accelerated sha256 code in a static libmd as it uses an
ifunc.

Reported by:	brd
Sponsored by:	The FreeBSD Foundation

Summary:
When running on a CPU that supports the arm64 sha256 intrinsics use them
to improve perfromance of sha256 calculations.

With this changethe following improvement has been seen on an Apple M1
with FreeBS running under Parallels, with similar results on a
Neoverse-N1 r3p1.

x sha256.orig
+ sha256.arm64
+--------------------------------------------------------------------+
|++                                                               x x|
|+++                                                              xxx|
||A                                                               |A||
+--------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x   5          3.41           3.5          3.46         3.458   0.042661458
+   5          0.47          0.54           0.5         0.504   0.027018512
Difference at 95.0% confidence
        -2.954 +/- 0.0520768
        -85.4251% +/- 0.826831%
        (Student's t, pooled s = 0.0357071)

Reviewed by:	cem
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D31284

r366344 fixed and reenabled the assembly optimized skein implementation,
but skein_block objects were not being rebuilt in no-clean builds. This
resulted in failing no-clean builds. SKEIN_USE_ASM controls which
routines come from C vs assembly, and with no explicit dependency
r366344's change to SKEIN_USE_ASM did not cause skein_block.{o,pico}
to be rebuilt.

Add a dependency on this Makefile for the skein_block objects. This
dependency is broader in scope than absolutely required (that is, the
skein_block objects will now be rebuilt on any change to this Makefile).
There are ways this could be addressed, but it is probably not worth the
additional effort or testing time to pursue them.

PR:		248221
Reported by:	kevans, Jeremy Faulkner
Discussed with:	kevans
Sponsored by:	The FreeBSD Foundation

The assembly implementation incorrectly used logical AND instead of
bitwise AND. Fix, and re-enable in libmd.

Submitted by:	Yang Zhong <yzhong@freebsdfoundation.org>
Reviewed by:	cem (earlier)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26614

It is apparently broken when assembled by contemporary GNU as as well as
Clang IAS (which is used in the default configuration).

PR:		248221
Reported by:	pizzamig
Sponsored by:	The FreeBSD Foundation