python: do not install the IDLE editor

IDLE is the Python IDE built with the tkinter GUI toolkit, for which
the main script has always been removed from the target (so it was
never usable in Buildroot). However, we were still installing about
800 to 900 KB of .pyc files used only by the idle editor. This commit
adds a Python patch that completely gets rid of the
compilation/installation of the idle editor. As a consequence, it is
no longer needed to manually remove the 'idle' program from the
target in python.mk.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>