Undoing the last Qtr_ hack

The Qtr_ hack isn't needed as in commit 720fc15b2dcd ("Introduce
QApplication") had already made sure that we are using gettext.

I didn't revert the two commits as I wanted to keep the added header
comments and fix the tooling in the Makefile as well.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>