package/jack2: drop dependency on host-python

host-python was listed in jack2 dependencies, but is actually
not needed. Also tested with an experimental python3 based
Waf package infrastructure, so we can exclude that jack2
"accidentally" uses the host-python2 pulled in by Waf.

Signed-off-by: Titouan Christophe <titouan.christophe@railnova.eu>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>