qmake: Evaluate extra configs before loading default_pre

Exclusive builds uses setExtraConfigs to apply the particular CONFIG
of each build pass. Unfortunately we were not applying these extra
configs early enough in QMakeEvaluator::visitProFile() for them to
be picked up/usable by default_pre, something that can be useful.

Change-Id: I423a4688250a15f0c1a2cc65a48f0bbc14ad4497
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
(cherry picked from qtbase/eea1c359c9663cec15e7373c065ee06cba151eed)
Reviewed-by: Daniel Teske <daniel.teske@digia.com>