Change use of ferror() in uClibc++ so that is does not use more capability than is currently supported by the NuttX ferror()

Fix error in AT91SAM SPI driver introduced in recent comment.  Varioius improvements to README files and debug output

Add support for a generic windows-based EABI toolchain; Add NX configuration to force default NXTK border colors

Correct border colors for SAM3U-EK border; clean up some comments; make sure that sam_vectors.S is identical to stam32_vectors.S

Remove CONFIG_XYZ_BUILTIN configurations, replace with the single CONFIG_NSH_BUILTIN_APPS.  Add SAM3/4 sam_periphclks.h which is just a header file that includes the right header file.  Misc SAM3U-EK cleanup