Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Similar commit in current:
(cherry picked from commit 95ee2897e98f)

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

(cherry picked from commit 4d846d260e2b9a3d4d0a701462568268cbfe7a5b)

In order to reduce code duplication move coredump support definitions
into the appropriate header and hide private definitions.

MFC after:		1 week

(cherry picked from commit 7446514533a40b376eaeb349ea33531ce9c711c2)

The SO_TIMESTAMPNS enables or disables the receiving of the SCM_TIMESTAMPNS
control message. The cmsg_data field is a struct timespec.
To distinguish between SO_TIMESTAMP and SO_TIMESTAMPNS in the recvmsg()
map the last one to the SO_BINTIME and convert bintime to the timespec.
In the rest, implementation is identical to the SO_TIMESTAMP.

MFC after:		2 weeks

(cherry picked from commit 71bc8bcf660b437b99af1e3d382f7bfdaea5fa9c)

To solve y2k38 problem in the recvmsg syscall the new SO_TIMESTAMP
constant were added on v5.1 Linux kernel. So, old 32-bit binaries
that knows only 32-bit time_t uses the old value of the constant,
and binaries that knows 64-bit time_t uses the new constant.

To determine what size of time_t type is expected by the user-space,
store requested value (SO_TIMESTAMP) in the process emuldata structure.

MFC after:		2 weeks

(cherry picked from commit 0e26e54bdfa2859908150011a4a165e9dd3de9ac)

To avoid annoyng messages from LTP test suites add the simple
implementation of /proc/self/oom_score_adj which is do nothing.

Reviewed by:		emaste
Differential revision:  https://reviews.freebsd.org/D34710
MFC after:		2 weeks

(cherry picked from commit b7df7b987e8fac05006aa5f132c424e2b2bcf156)

In preparation for clone3 system call add struct clone_args and use it in
clone implementation.
Move all of clone related bits to the newly created linux_fork.h header.

Differential revision:	https://reviews.freebsd.org/D31474
MFC after:		2 weeks

(cherry picked from commit 0a4b664ae8582b7596858317b53d84eb4f8bbf9a)

Add email and fixup years while here.

Reviewed by:		imp
Differential Revision:	https://reviews.freebsd.org/D30912
MFC after:		2 weeks

(cherry picked from commit 1ca6b15bbdcebd6a0726dae2e9b72f383139d16c)

Implement dumping core for Linux binaries on amd64, for both
32- and 64-bit executables.  Some bits are still missing.

This is based on a prototype by chuck@.

Reviewed By:	kib
Sponsored By:	EPSRC
Differential Revision:	https://reviews.freebsd.org/D30019

(cherry picked from commit 447636e43c08d697664512a50f00f93f41c0a79f)

Current epoll implementation stores udata fields of epoll_event
structure in special dynamically-sized table rather than in udata field
of backing kevent structure because of 2 reasons:
1. Kevent's udata size is smaller than epoll's on 32-bit archs.
2. Kevent's udata can be clobbered on execution EPOLL_CTL_ADD as kqueue
   modifies existing event while epoll returns error in this case.

After r320043 has introduced four new 64bit user data members (ext[]),
we can store epoll udata in one of them and drop aforementioned table.
According to kqueue_register() source code ext members are not updated
when existing kevent is modified that fixes p.2.

As a side effect the patch fixes PR/252582.

Reviewed by:	trasz
MFC after:	1 month
Differential revision:	https://reviews.freebsd.org/D28169

(cherry picked from commit b3c6fe663bb90240f8bda6b5ba9c6a761f09f078)