tools/makemanifest.py: Use os.makedirs to make path for generated files.
tools/makemanifest.py: Use os.makedirs to make path for generated files.

The existing implementation of mkdir() in this file is not sophisticated
enough to work correctly on all operating systems (eg Mac can raise
EISDIR).  Using the standard os.makedirs() function handles all cases
correctly.

Signed-off-by: Damien George <99e6b749acbfbe2a596df99e91d24d6e1fdbee00@micropython.org>

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