pycompile: allow to force compilation

pycompile: allow to force compilation

By default, compile_dir() relies on the modification time to know if a
python file has to be built again. However in some circumstances (when
doing reproducible builds), modification times are not reliable. Thus,
this patch adds a way to force the rebuild of all python sources.

Signed-off-by: Jérôme Pouiller <jezz@sysmic.org>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>