Revert "Disable gui tests on Mac for now"

This reverts commit 8ed38c70fd29680f7981d9d23581d46cf32139d0.

Task-number: QTBUG-35344

Conflicts:
	tests/auto/auto.pro
	tests/auto/qml/debugger/debugger.pro

Change-Id: I57bec5d7ede879e24ba2b0618333b4e4110c41df
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Reviewed-by: Liang Qi <liang.qi@digia.com>