[arch-general] Include paths for python 3

I've noticed that the include paths for python 3 are updated according to the version of python being installed. This removes some stability for custom programs which build against python (example boost.python). It would be nice if there was a symlink version of python include paths to a stable location like `/usr/include/python3`. Thank you. -- Cheers Jayesh Badwaik https://jayeshbadwaik.gitlab.io