Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC 246805:
Make VM_NDOMAIN a kernel option so that it can be enabled from a kernel
config file.

MFC 229427:
Fix a few bugs in the SRAT parsing code:
- Actually increment ndomain when building our list of known domains
so that we can properly renumber them to be 0-based and dense.
- If the number of domains exceeds the configured maximum (VM_NDOMAIN),
bail out of processing the SRAT and disable NUMA rather than hitting an
obscure panic later.
- Don't bother parsing the SRAT at all if VM_NDOMAIN is set to 1 to
disable NUMA (the default).

MFC 226039:
Ignore SRAT memory entries if the memory range does not overlap with an
existing phys_avail[] entry. If a hw.physmem setting causes a memory
domain to not be present in phys_avail[], the SRAT table will now be
ignored rather than triggering a panic when a CPU in the missing domain
tries to allocate a page.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

When performing a sanity check on the SRAT table to ensure that each
memory domain has an assigned CPU, ignore disabled CPUs. Previously
disabled CPUs were counted as being in domain 0.

Reported by: mdf

Add a parser for the ACPI SRAT table for amd64 and i386. It sets
PCPU(domain) for each CPU and populates a mem_affinity array suitable
for the NUMA support in the physical memory allocator.

Reviewed by: alc