python3: switch to Git formatted patches

In preparation for the bump to Python 3.5.0, let's switch all the
patches to the Git format. This way, a Git repository of the Python
source code can be used to manage those patches, which makes it easier
to bump to newer Python versions.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>