python, python3: add patch to prevent distutils from adjusting the shebang

The copy_scripts() method in distutils copies the scripts listed
in the setup file and adjusts the first line to refer to the
current Python interpreter. When cross-compiling, this means that
the adjusted shebang refers to the host Python interpreter.

As a consequence, we add a patch for python and python3 that
force copy_scripts() to preserve the shebang when
cross-compilation is detected.

Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>