py/makeqstrdefs.py: Process C++ files as well.
py/makeqstrdefs.py: Process C++ files as well.

Preprocessed C++ code isn't different from C code when it comes to QSTR
instances so process it as well.

henriknelson/micropython,bvernoux/micropython,henriknelson/micropython,MrSurly/micropython,adafruit/circuitpython,henriknelson/micropython,adafruit/circuitpython,adafruit/circuitpython,bvernoux/micropython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,MrSurly/micropython,MrSurly/micropython,MrSurly/micropython,henriknelson/micropython,adafruit/circuitpython,MrSurly/micropython,adafruit/circuitpython,bvernoux/micropython,henriknelson/micropython