Beginning of logic that will, hopefully, all me to build applications against a NuttX export package (vs. the nuttx/ source tree).

The ELF test/example has been extended so the individual ELF test programs can link against the SYSCALL library (if it is available) or against the C library to eliminate or minimize the need for symbol tables (2014-8-29).

STM32 FLASH fixes: use size_t instead of uint16_t, make interface more generic.  From Freddie Chopin

wdog.h does not contain any application interface, only internal OS interface.  Further, it is non-standard.  Move wdog.h from include/ to include/nuttx. For the same reason, move the description of the watchdog timer interfaces from the Users Guide to the Porting Guide.

Change the way PHY interrupts work: disable automatically.  Then we have to re-subscribe each time after the interrupt fires

NSH net monitor:  use a seamphore instead of boolean; use sem_timedwait instead of a boolean to communicate

Extend the NSH network initialization logic.  There is now an option that will create a network monitor thread that will monitor the state of the link.  When the link goes down, the code will attempt to gracefully put the Ethernet driver in a down state; When the link comes back, the code will attempt to bring the network back up.

More of the PHY event notification logic change:  Fix some compile errors when full feature is enabled; Add some missing ioctol logic