MFC: r346717: Make bhyve SMBIOS table topology aware

When the CPU Topology was added to bhyve in r332298 the SMBIOS table was
missed, this table passes topology information to the system and was still
using the old concept of each vCPU is a socket with 1 core and 1 thread.
This code did not even try to use the old sysctl information to adjust
this data.

Correct that by building a proper SMBios table, mapping the > 254 cases to
0 per the SMBios 2.6 specification that is claimed by the structure.

Approved by: re (kib)

MFC r326276:

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.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Correct display of bhyve SMBIOS UUIDs with dmidecode by bumping the version.

The mixed little/big-endianness of SMBIOS UUIDs was clarified in v2.6
of the SMBIOS spec. dmidecode uses the reported version of SMBIOS to
determine the layout and what to byte-swap.

bhyve's SMBIOS reported as 2.4 though it implemented the 2.6-style of
memory layout. This resulted in dmidecode reporting a different
UUID than one passed in via the -U option.

Fix by exporting a version of 2.6.

Reviewed by: tychon
Reported by: julian
MFC after: 1 day

Set the version and date to fixed fields rather than using
preprocessor macros that don't allow reproducible builds.
As a side-effect, the date string is now spec-compliant.

root@bhyve:~ # dmidecode
# dmidecode 2.12
SMBIOS 2.4 present.
12 structures occupying 514 bytes.
Table at 0x000F101F.

Handle 0x0001, DMI type 0, 24 bytes
BIOS Information
Vendor: BHYVE
Version: 1.0
Release Date: 03/14/2014

Submitted by: des (original version)
Reviewed by: tychon
MFC after: 1 week

Provide APIs to directly get 'lowmem' and 'highmem' size directly.

Previously the sizes were inferred indirectly based on the size of the mappings
at 0 and 4GB respectively. This works fine as long as size of the allocation is
identical to the size of the mapping in the guest's address space. However, if
the mapping is disjoint then this assumption falls apart (e.g., due to the
legacy BIOS hole between 640KB and 1MB).

Add SMBIOS support.

A new option, -U, can be used to set the UUID in the System
Information (Type 1) structure. Manpage fix to follow.

Approved by: grehan (co-mentor)