Remove $FreeBSD$: two-line .h pattern

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

spdx: The BSD-2-Clause-NetBSD identifier is obsolete, drop -NetBSD

The SPDX folks have obsoleted the BSD-2-Clause-NetBSD 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

makefs: whitespace cleanup (remove space before tab)

MFC after: 1 week

Synchronise with NetBSD's version of EFI handling for El Torito images.

When I implemented my EFI support I failed to check if the upstream version
of makefs in NetBSD had done the same. Override my version with theirs to
make it easier to stay in sync with them in the future.

Reviewed by: imp, mav
Obtained from: NetBSD
MFC after: 1 week
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D14913

Allow makefs to properly tag UEFI El Torito boot images. Use them in amd64 ISOs.

UEFI booting requires an EFI System Partition (ESP). On most storage devices
this will be in a specific partition type. To allow booting from CD/ISO
filesystems, UEFI will look for an ESP in the form of a FAT filesystem image
embedded in the image. Historically FreeBSD has added one of these to its
amd64 ISO images but marked it as simply another i386 boot image. Luckily for
us most UEFI implementations are rather forgiving and work this out for us.

This change adds the ability to mark a boot image as being a UEFI image. It
also modifies our ISO generation to use this marking for the UEFI image we
embed.

Reported by: Thomas Schmitt <scdbackup@gmx.net>
Reviewed by: emaste, imp
MFC after: 1 week
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D14809

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

Sync with the latest version from NetBSD. It notably addds ISO9660 support.

Submitted by: bapt