Fix python3's `compileall` command for build.py file
Fix python3's `compileall` command for build.py file

Because as of Python 3.5, the .pyo filename extension is no longer used, see:
  - `PEP 488 -- Elimination of PYO files` (https://www.python.org/dev/peps/pep-0488/)
  - `PEP 3147 -- PYC Repository Directories` as to why a separate directory is used (https://www.python.org/dev/peps/pep-3147/)

Also moves comment to the right place

kivy/python-for-android,PKRoma/python-for-android,kivy/python-for-android,rnixx/python-for-android,rnixx/python-for-android,kivy/python-for-android,rnixx/python-for-android,kronenpj/python-for-android,germn/python-for-android,germn/python-for-android,germn/python-for-android,germn/python-for-android,germn/python-for-android,kronenpj/python-for-android,PKRoma/python-for-android,PKRoma/python-for-android,kronenpj/python-for-android,rnixx/python-for-android,kivy/python-for-android,kronenpj/python-for-android,rnixx/python-for-android,rnixx/python-for-android,germn/python-for-android,kivy/python-for-android,PKRoma/python-for-android,kronenpj/python-for-android,PKRoma/python-for-android