Pay attention to TCP_NODELAY when it's set/unset after the connection
is established.

MFC after:	1 day
Enable the station-side power management flag.

It's not enabled by default in net80211 so this is a no-op unless
if you enable it (ifconfig wlan0 powersave).

Tested:

* iwn0: <Intel WiFi Link 5100> mem 0xf4300000-0xf4301fff irq 17 at device 0.0 on pci3

TODO:

* .. test on all the other NICs
* See if I have to disable it during scan and such
* Make it configurable live, rather than only after it's done its initial
  receive calibration.
When processing an incoming ABORT, SHUTDOWN_COMPLETE or ERROR (NAT related)
chunk, take always the T-bit into account, when checking the verification
tag.

MFC after: 3 days
Add nodes for PWMSS1 and PWMSS2
Pull in r185594 from llvm trunk:

  Add MachineBasicBlock::addLiveIn().

  This function adds a live-in physical register to an MBB and ensures
  that it is copied to a virtual register immediately.

Pull in r185615 from llvm trunk:

  Live-in copies go *after* EH_LABELs.

  This will soon be tested by exception handling working at all.

Pull in r185617 from llvm trunk:

  Simplify landing pad lowering.

  Stop using the ISD::EXCEPTIONADDR and ISD::EHSELECTION when lowering
  landing pad arguments. These nodes were previously legalized into
  CopyFromReg nodes, but that never worked properly because the
  CopyFromReg node weren't guaranteed to be  scheduled at the top of the
  basic block.

  This meant the exception pointer and selector registers could be
  clobbered before being copied to a virtual register.

  This patch copies the two physical registers to virtual registers at
  the beginning of the basic block, and lowers the landingpad instruction
  directly to two CopyFromReg nodes reading the *virtual* registers. This
  is safe because virtual registers don't get clobbered.

  A future patch will remove the ISD::EXCEPTIONADDR and ISD::EHSELECTION
  nodes.

Together, these changes fix llvm PR 16038 ('qt4 webcore file results in
"Bad machine code: Using an undefined physical register"'), and should
make it possible again to compile the www/qt4-webkit port again on the
i386 arch, without using a CPUTYPE=i686 or higher setting.
Implement $probe_only for the media access modules. sysinstall(8) was
allowed to ignore the probe_only argument of its member functions solely
because in the C language, the file accessor methods open and return a file
descriptor and reading of the data is optional. In shell, the file accessor
methods return data on stdout and that data should not be ignored (large
files could block execution).

So, we must adhere to the probe_only flags and in some cases (in the case of
FTP, for example) change the `get' strategy to simply test existence and
return an appropriate status.

This was required because the up-coming package management stuff makes heavy
use of the probe_only argument to try different package suffixes. Every
media access module must implement $probe_only for the `get' accessor.
Add support for ePWM submodule of PWMSS

ePWM is controlled by sysctl nodes dev.am335x_pwm.N.period,
dev.am335x_pwm.N.dutyA and dev.am335x_pwm.N.dutyB that controls
PWM period and duty cycles for channels A and B respectively.

Period and duty cycle are measured in clock ticks. Default
clock frequency for AM335x PWM subsystem is 100MHz
On-the-fly changes to the interrupt coalescing timer should apply to the
TOE rx queues too.

MFC after:	1 day