ci: travis: switch mingw cross build to also use Fedora 29 as base

Summary:
The new image also contains the ewpi install in a different location.
Updating the references here.

Reviewers: bu5hm4n, zmike

Reviewed By: zmike

Subscribers: cedric, reviewers, committers

Tags: efl

Differential Revision: https://phab.enlightenment.org/D7833