Kconfig files:  All USB-related options depend on CONFIG_LIB_BOARDCTRL and now set CONFIG_BOARDCTL_USBDEVCTL=y

minor; intialize buffer to well-known pattern to make it easy to see if it was truly filled with random data

minor; intialize buffer to well-known patter to make it easy to see if it was truly filled with random data

Add a simple test of the scheduler instrumentation logic.  This initial version is still kind of buggy.

apps/modbus/nuttx/portserial.c:  Was not returning an error on failure to open the device driver.  From Olololshka kokoko