Add scc(4), a driver for serial communications controllers. These
controllers typically have multiple channels and support a number
of serial communications protocols. The scc(4) driver is itself
an umbrella driver that delegates the control over each channel
and mode to a subordinate driver (like uart(4)).
The scc(4) driver supports the Siemens SAB 82532 and the Zilog
Z8530 and replaces puc(4) for these devices.
Add support for scc(4).
o  Add scc(4) to the build.
o  Add the scc(4) manpage to the build.
o  Update the uart(4) manpage to account for scc(4).
o  Update the uart(4) module build to include support for scc(4).
Add scc(4).
When we attach to either a SAB82532 or a Z8530, print a notice
saying that scc(4) should be configured into the kernel. This
helps people to migrate away from puc(4) for these devices.
Fix a panic on sparc64 related to inproper aligment - we cannot assume,
that 'unsigned char *' argument is 4 byte aligned.

MFC after:	3 days
Revert previous change, as I fixed MD5(9).
Fix more stack corruptions on amd64.

Vararg functions have a different calling convention than regular
functions on amd64. Casting a varag function to a regular one to
match the function pointer declaration will hide the varargs from
the caller and we will end up with an incorrectly setup stack.

Entirely remove the varargs from these functions and change the
functions to match the declaration of the function pointers.
Remove the now unnecessary casts.

Also change static struct ipprotosw[] to two independent
protosw/ip6protosw definitions to remove an unnecessary cast.

PR:				amd64/95008
Submitted and tested by:	Mats Palmgren
Reviewed by:			rwatson
MFC after:			3 days
Revert to using acpi_max_threads instead of the hardcoded value of '3'.
Expose res_update and friends again.  At least, ports/mail/spamilter
uses them.
Now, we have res_nupdate and res_nmkupdate as well, but they are
still based on our old resolver for binary backward compatibility.
So, they don't provide new features such as TSIG support.

Reported by:	pointyhat via kris
Optimize runtime performance, primary using the following techniques:

  * Avoid choosing an arena until it's certain that an arena is needed
    for allocation.

  * Convert division/multiplication to bitshifting where possible.

  * Avoid accessing TLS variables in single-threaded code.

  * Reduce the amount of pointer dereferencing.

  * Move lock acquisition in critical paths to only protect the the code
    that requires synchronization, and completely remove locking where
    possible.
Currently, if writing out a log entry fails, we unlink that log entry from our
internal list of logfiles. So if writev(2) fails for potentially transient
errors like ENOSPC, syslogd requires a restart, even if the filesystem has
purged.

This change allows syslogd to ignore ENOSPC space errors, so that when the
filesystem is cleaned up, syslogd will automatically start logging again
without requiring the reset. This makes syslogd(8) a bit more reliable.

MFC after:	1 week
Include the sbus attachment of scc(1) when either fhc(4) or sbus(4)
is configured.
fixup error handling in taskqueue_start_threads: check for kthread_create
failing, print a message when we fail for some reason as most callers do
not check the return value (e.g. 'cuz they're called from SYSINIT)

Reviewed by:	scottl
MFC after:	1 week
remove these vestiges of gdbserver.. It hasn't built in a long time, and
now really belongs in gdb, not binutils..  Plus, these don't resemble what
the new gdbserver looks like.
Add a dummy implementation of bus_space_map().
Allow uart(4) to be built on PowerPC.
Build uart(4) on PowerPC.
 - Add the B_NEEDSGIANT flag which is only set if the vnode that owns a buf
   requires Giant.  It is set in bgetvp and cleared in brelvp.
 - Create QUEUE_DIRTY_GIANT for dirty buffers that require giant.
 - In the buf daemon, only grab giant when processing QUEUE_DIRTY_GIANT and
   only if we think there are buffers in that queue.

Sponsored by:	Isilon Systems, Inc.
 - LK_RETRY means nothing when passed to VOP_LOCK.  Call vn_lock instead.
 - Move the vn_lock of the dvp until after we've unbusied the filesystem
   to avoid a LOR with the mount point lock.
 - In the v_mountedhere while loop we acquire a new instance of giant each
   time through without releasing the first.  This would cause us to leak
   Giant.

Sponsored by:	Isilon Systems, Inc.