Add simulator configuration for testing the Union Fs.  Fix a few bugs.  Almost works but still too flaky

Add support for a union file system that can be used to overlay and merge the content of two mounted file systems.

Damn.  THTTPD will not yet run with binfs because it wants an index.html file.  THTTPD does support indexing directories if CONFIG_THTTPD_GENERATE_INDICES=y, but there are some compilation issues that need to be fixed when that option is selected.

Olimex LPC1766STK.  Add an example configuration showing how to build apps/netutils/thttpd using binfs

Add support uClibc++ excpetions.  This involves additional handling for relative relation types, additional support for unwinding, as well as additional changes.  The culmination of a big effort fromo Leo Aloe3132

LPC17xx: All configurations that had the LPC17xx ethernet driver enabled have CONFIG_NET_NOTINTS=y enabled and also the HP worked which is now needed in those configurations

Add an option to disable support for long long formats in lib_vsprintf.  From Alan Carvalho de Assis

STM32 F4 Discovery: Move up_cxxinitialize from nuttx/configs/stm32f4discovery/src to apps/platform/stm32f4discovery where it belongs.

Extend device specific callbacks to ICMPv6 and ARP.  Fix some IPv6 compilation errors that have crept in

SAML21-Xlplained: Add options to enable XOSC32K and to use it as the DFLL source; NSH configure now uses DFLL with OSC16M source

All minnsh configurations: Removing CONFIG_ARCH_STACKDUMP we reduce more 424 bytes.  Alan Carvalho de Assis

LPCXpresso-LPC1115:  Add a minimal NSH configuration that has the file system disabled.  Update README with OpenOCD instructions.  From Alan Carvalho de Assis.