Don't complain about strict aliasing for Travis builds

Python's own macros make use of type punning (like Py_RETURN_NONE)

Change-Id: Iaf790f36583802224738a06b94a867c7177c2a4f
Reviewed-on: http://review.couchbase.org/41502
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Volker Mische <volker.mische@gmail.com>