AR933x UART updates:

* Default clock is 25MHz;
* Remove the UART register macro here - it's not needed as we don't need
  to "adjust" the register offset / spacing at all;
* Remove unused fields in the softc.

Tested:

* AP121


git-svn-id: svn://svn.freebsd.org/base/head@248926 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
AR933x CPU device improvements:

* Add baud rate and divisor programming code. See below for more
  information.

* Flesh out ar933x_init() to disable interrupts and program the initial
  console setup.

* Remove #if 0'ed code from ar933x_term().

* Explain what these functions do.

Now, the baud rate and divisor code comes from Linux, as a submission
to the OpenWRT project and Linux kernel from
Gabor Juhos <juhosg@openwrt.org>.

The original ticket for this code is https://dev.openwrt.org/ticket/12031 .

I've contacted Gabor and asked for his permission to also licence the patch
in question (which covers this code) to BSD lience and he's agreed.
Hence why I'm including it here in FreeBSD.

Tested:

* AP121 (AR9330)


git-svn-id: svn://svn.freebsd.org/base/head@248927 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Improve namespacing in <sys/socket.h>:

 * MSG_NOSIGNAL is in POSIX.1-2008.
 * MSG_NOTIFICATION (SCTP) is not in POSIX.
 * PRU_FLUSH_* (SCTP) are not in POSIX.
 * bindat()/connectat() are not in POSIX.

Discussed with:	rrs (PRU_FLUSH_*)


git-svn-id: svn://svn.freebsd.org/base/head@248932 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Use a shared lock for VOP_GETEXTATTR, as it is a read-like operation.

MFC after:	1 week


git-svn-id: svn://svn.freebsd.org/base/head@248933 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Initialize sym_count to 0.

This fixes a compiler warning introduced in r248121.


git-svn-id: svn://svn.freebsd.org/base/head@248934 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add some more stats to keep track of all the reasons that a vcpu is exiting.


git-svn-id: svn://svn.freebsd.org/base/head@248935 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
When building universe ensure the required worlds are finished before
starting the kernels. Before this the kernels would be built as part of the
last architecture universe target. There can cause problems when this world
finishes before the other worlds as the host compiler may be picked up
rather than the target compiler.

The solution is to add a target to build the universe kernels that depends
on all the world targets finishing. As we may not be building a world only
depend on it when MAKE_JUST_KERNELS is undefined.


git-svn-id: svn://svn.freebsd.org/base/head@248937 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Merge remote-tracking branch 'upstream/master'