This removes Python-related build variants, and adds
PYTHON3_PKG_BUILD:=0 and minor build adjustments (where appropriate),
for non-Python packages. There should be no changes to build output.

This also updates some include paths for python3-package.mk and/or
python3-host.mk to be relative to the package Makefile.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

Convert bigclown packages to use pypi.mk and pypi in general instead of
github.

This allows us to remove version replacement as that is already done in
pypi archive.

Updated dependencies to also contain proxy dependencies that are listed
in upstream.

Signed-off-by: Karel Kočí <karel.koci@nic.cz>

Signed-off-by: Karel Kočí <karel.koci@nic.cz>