drivers/sensors/max31855: Add multiple max31855 sensors feature and support for bambino-200e and stm32f4discovery

apps/examples/usbterm is gone because it can be configured to perform an illegal call into the OS.  Remove all traces of CONFIG_EXAMPLES_USBTERM* and all of the illegal device support.

Eliminate CONFIG_ARCH_OPTIMIZED_FUNCTIONS.  Move options to select architectur-specific C library options from libc/Kconfig to libc/machine/Kconfig and rename.

libc/hex2bin:  Move the portable library portion of apps/system/hex2bin to nuttx/libc/hex2bin where it can be shared with the OS internals.

Add configuration files that have CONFIG_CDCACM=y (and not CONFIG_CDCACM_COMPOSITE) must have CONFIG_LIB_BOARDCTL=y and CONFIG_BOARD_USBDEVCTRL=y

Rename CONFIG_ARMV7M_MPU to CONFIG_ARM_MPU so that we can reuse the configuration settings for the ARMV7R MPU