Add two sysctls for newly added tunables.

MFC after:	2 weeks
Split the XHCI TRB allocations into smaller parts, so that we don't
end up allocating contiguous busdma buffers above PAGE_SIZE bytes.

MFC after:	1 week
Tested by:	Ruslan Bukin <br@bsdpad.com>
Port the rwsnoop DTrace Toolkit script to FreeBSD.
Remove dependency on the Korn Shell.
Remove Zones in favor of Jails.
Remove support (for now) for filename printing.
Remove debugging options from the rwsnoop script.
The accept filter code is not specific to the FreeBSD IPv4 network stack,
so it really should not be under "optional inet". The fact that uipc_accf.c
lives under kern/ lends some weight to making it a "standard" file.

Moving kern/uipc_accf.c from "optional inet" to "standard" eliminates the
need for #ifdef INET in kern/uipc_socket.c.

Also, this meant the net.inet.accf.unloadable sysctl needed to move, as
net.inet does not exist without networking compiled in (as it lives in
netinet/in_proto.c.) The new sysctl has been named net.accf.unloadable.

In order to support existing accept filter sysctls, the net.inet.accf node
has been added netinet/in_proto.c.

Submitted by:	Steve Kiernan <stevek@juniper.net>
Obtained from:	Juniper Networks, Inc.
Further improvements on elfdump, to follow up r269092:

- Add ARM specific section header types.
- Add SHT_GNU_HASH section header type.
- Improve reporting of undefined tags in d_tags.
- Add DT_GNU_HASH tag.

Reviewed by:	emaste
Since we cannot yet display the name print the file descriptor so that
it can be looked up manually using procstat(1).
Update the header printing to match the rest of the output.

Pointed out by: mdf
store the AR9300 interrupts away when doing interrupt debugging.
Add another revision of the AR8327.
Commit some sins in the name of "oh god oh god I don't really want to
be able to claim I know how the UART code works."

* Just return 115200 as the current baud rate. I should cache it in the
  device struct and return that but I'm lazy right now.
* don't error out on other ioctl settings for now, just silently ignore them.
* remove some code that was copied from the 8250 driver that isn't needed
  any longer.

Tested:

* AR9331, Carambola-2 board.
Fix several cases of NULL dereference when INQUIRY sent to absent LUN.

MFC after:	3 days
Add support for my Lenovo T400.

Tested:

* Lenovo T400, model w/ P8700 Intel CPU on-board
Give loaders more control over the Forth initialization process. In
particular, allow loaders to define the name of the RC script the
interpreter needs to use. Use this new-found control to have the
PXE loader (when compiled with TFTP support and not NFS support)
read from ${bootfile}.4th, where ${bootfile} is the name of the
file fetched by the PXE firmware.

The normal startup process involves reading the following files:
1.  /boot/boot.4th
2.  /boot/loader.rc or alternatively /boot/boot.conf

When these come from a FreeBSD-defined file system, this is all
good. But when we boot over the network, subdirectories and fixed
file names are often painful to administrators and there's really
no way for them to change the behaviour of the loader.

Obtained from:	Juniper Networks, Inc.
1.  Suppress output for the TFTP-based PXE loader, but leave it in
    place for the NFS-based PXE loader. Information like rootpath
    or rootip aren't that useful for TFTP and the gateway IP is
    typically already printed by the firmware.
2.  Only set boot.nfsroot.* environment variables for NFS. This
    makes it possible for the OS to work either way by checking
    for the presence or absence of environment variables.
3.  Set boot.netif.server when using TFTP so that the OS can fetch
    files as well. A typical use case for this is network-based
    installations with the installation process implemented on
    top of FreeBSD.
4.  The pxelinux loader has a set of alternative names it tries
    for configuration files. Make it easier to do something
    similar in Forth by providing the IP address as a 32-bit hex
    number in the pxeboot.ip variable and the MAC address with
    dashes in the pxeboot.hwaddr environment variable.

Obtained from:	Juniper Networks, Inc.
Forced commit - testing commit mail etc pipelines.
Update from mav@ - don't break the input switching.
Correct the locking statement.

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Remove man page for non-existent VOPs.

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Explicitely mention that inactivated or reclaimed vnode is locked
exclusively.

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days