sys: Remove $FreeBSD$: two-line .h pattern

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

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

sys/x86: further 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.

Use fixed-width types for all fields in MP Table structures and pack
all the structures. While here, move a helper struct only used in
the kernel parser out of this header since it is not part of the MP
specification itself.

Fix the processor table entry structure to use a fixed-width type for
32-bit fields so it is the correct size on amd64. Remove a workaround
for the broken structure from bhyve(8).

MFC after: 1 week

Fix build when NEW_PCIB is not defined.

Submitted by: gcooper (partially)
Pointy hat to: jhb

Respect the BIOS/firmware's notion of acceptable address ranges for PCI
resource allocation on x86 platforms:
- Add a new helper API that Host-PCI bridge drivers can use to restrict
resource allocation requests to a set of address ranges for different
resource types.
- For the ACPI Host-PCI bridge driver, use Producer address range resources
in _CRS to enumerate valid address ranges for a given Host-PCI bridge.
This can be disabled by including "hostres" in the debug.acpi.disabled
tunable.
- For the MPTable Host-PCI bridge driver, use entries in the extended
MPTable to determine the valid address ranges for a given Host-PCI
bridge. This required adding code to parse extended table entries.

Similar to the new PCI-PCI bridge driver, these changes are only enabled
if the NEW_PCIB kernel option is enabled (which is enabled by default on
amd64 and i386).

Approved by: re (kib)

Move the mptable.h under x86/include/.

Sponsored by: Sandvine Incorporated
MFC after: 14 days