jan-kiszka tools: Allow to build jailhouse-config-collect independent of PYTHON_…
…PIP_USABLE

This allows to generate the config collector on a host that has no
sufficient pip support to install the Python tools - which can be
perfectly fine.

Reported-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Latest commit 37bc6c1 Jul 12, 2018