This adds a script that searches a Python package's source code to find
imports for separately-packaged standard library modules.
The script can be run by calling make with the configure target and
"PY3=stdlib V=s" arguments, e.g.
make package/python3-lxml/configure PY3=stdlib V=s
This also updates the readme on how to call this script, as well as more
information on Python package dependencies in general.
Signed-off-by: Jeffery To <jeffery.to@gmail.com>
