Fix building for i386

[shoffmeister]

Fix the build infrastructure to build i386.

At the same time, this sneaks in two slightly unrelated changes:

• make the buildTest and mockTest runs depend on (the success of) the makeTest job; this results in early failure in case something goes wrong
• add "set -e" everywhere to fail scripts immediately; this uncovered dnf-builddep being used, which does not exist

Generally it would seem as if the i386 builds might have been broken one way or the other; theoretically the i386 rpm now contains i386 artefacts, but I am not setup to properly test this.

Generally speaking, it might be worthwhile removing build support for simplicity, see #210

[elguero]

Thanks! Looks good.