Connection pool bugfix

This is only seen if you try to call amqp.cleanup().

Change-Id: I5c14a21987b4b7aeca7dddc91d7c8b2510edefeb
Add missing gettextutils

We don't need this in oslo.messaging itself, but excutils and sslutils
do use it.

Change-Id: Ib35caa6616aab7be1a7f872b2073f7b9f606b258