Don't use "qmake-qt4" as qmake

Tomaz' commit 009e6a6fa7055ed0ef14e4b4d9407999d86ef158 introduced
qmake-qt4 instead of qmake.  Oops.

Signed-off-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>