Fix a problem in clock_systimer64 that occurs when (1) the 64-bit system time is enabled, and (2) the value of CONFIG_USEC_PER_TICK is less than 1 millisconds (such as when using the tickless mode of operation).  In that case, the convertion of time to 64-bit millisecond value in clock_systmer64() causes some bad times to be returned.  Time was converted to milliseconds, then to configured ticks.  Precision was lost in the millisecond convertion.

The fix is to first convert time to a 64-bit microsecond value, then to the configured tick value.

Noted by David Sidrane.

Viewtool STM32F107: Add support for an optional, add-on Freescale MPL115A baramoter.  From Alan Carvalho de Assis

gettimeofday() and settimeofday():  Move gittimeofdady() from sched/clock to libc/time.  All remove gettimeofday() from NuttX system calls.  It is only a wrapper around clock_settime() and does not need a trap.  gettimeofday() is no longer tried as a core OS interface.

gettimeofday has been decremented in POSIX 2008.  settimeofday() was never part of POSIX, but I decided to add it to libc as well just for symmetry.

LPC17xx:  Add IPv6 support to the LPC17 Ethernet driver.  Untested... I no longer have a proper environment for LPC17 debug.

SAM4 Ethernet Driver:  No supports operation using the high priority work queue so that packet processing can occur outside of interrupt level processing.

SAM4E-EK: The nsh configuration now configures the Ethernet driver for execution on the HP work thread.

IOB Configuration:  Default number of IOB changes must be more than zero is UDP read-ahead is enabled.