add ARDUINO_ARCH_RTTHREAD to support RT-Thread/RTduino
RT-Thread is a opensource RTOS, and now RT-Thread software packages has fully support most of the Adafruit Arduino libraries, so that Adafruit Arduino libraries can directly run on RT-Thread BSPs: https://packages.rt-thread.org/en/search.html?search=adafruit
add ARDUINO_ARCH_RTTHREAD to support RT-Thread/RTduino
RT-Thread is a opensource RTOS, and now RT-Thread software packages has fully support most of the Adafruit Arduino libraries, so that Adafruit Arduino libraries can directly run on RT-Thread BSPs: https://packages.rt-thread.org/en/search.html?search=adafruit
https://github.com/RT-Thread/rt-thread https://github.com/RTduino/RTduino