MAKEDEV: New `virtio' target for all virtio-related devices.

We can use this to add more as they come up so we don't have to keep
tweaking every etc.${MACHINE}/MAKEDEV.conf every time. Currently
this makes nodes for viocon(4) and vio9p(4).

(Not all GENERIC kernels enable vio9p(4) but I suspect the ones that
don't really should; for those that are disabled because PAGE_SIZE !=
4096, I expect it's just a matter of some additional indexing to make
vio9p(4) work with other page sizes.)

PR kern/59211: vio9p(4): missing from various GENERICs and MAKEDEVs

branches: 1.10.2;
MAKEDEV: Tidy some entries on x86 and Arm.

While here, reduce some diffs arising from ordering and formatting
between these architectures.

Only difference between evbarm and aarch64 now is /dev/vchiq. Not
sure offhand if it makes sense on aarch64 or only 32-bit Arm.

PR port-amd64/58093: /dev/efi missing on x86
PR port-arm/58100: /dev/ttyVI* missing on aarch64
PR port-arm/58101: /dev/nvme* missing on aarch64
PR port-arm/58102: /dev/raid* missing on aarch64

branches: 1.9.2;
smbios: Add character device for accessing SMBIOS tables

The /dev/smbios character device gives an aperture into physical memory
that allows read-only access to the SMBIOS header and tables.

acpi: add character device for accessing ACPI tables

The /dev/acpi character device gives an aperture into physical memory
that allows only read access to known ACPI tables: RSDP, XSDT/RSDT, and
the root tables. Adapt acpidump(8) to use this interface by default,
falling back to the old /dev/mem method if it is not available or if
ACPIDUMP_USE_DEVMEM=1 is set in the environment. The user visible benefit
of this change is that "options INSECURE" is no longer required to
dump ACPI tables.

add tprof

Create ld[4-7] device nodes, matching evbarm

Remove ISDN from the kernel. It has remained unmaintained for a long time,
is of poor quality, and is now an obstacle to MP-ification. It was removed
ten years ago from FreeBSD for the same reason.

This retires a big user of the mbuf API, and will ease maintenance of the
kernel.

branches: 1.4.2;
Create bpf and openfirm devices

branches: 1.3.12;
spkr->speaker. Found by kamil@

Add a synthesized pc beeper and keyboard bell for platforms with an audio
device.

branches: 1.1.4; 1.1.8;
Preliminary files for AARCH64 (64-bit ARM) support.
Enough for a distribution build.