python3: suffix vars with 3

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
python: use $(LN) instead of 'ln -sf'

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
python: add python2 symlink to python as per PEP394

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
python3: add python3 symlink to python exec as per PEP394

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
python3: fix python host path

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>