python3: bump to 3.4.2

This commit bumps python3 to Python 3.4.2. Two patches had to be
changed slightly to fix some minor conflicts.

PYTHON3_LIBTOOL_PATH = NO was added to prevent Buildroot from trying
to patch a version of libtool for which we don't have matching
patches, which isn't a problem since we're anyway not using the part
of the Python sources that uses libtool (it's the built-in copy of
libffi, and we use the external libffi).

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>