Don't try to build qt_app in release against debug-only Qt builds

Change-Id: I575e019db76dadcf7586e18809e6f67545759974
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
iOS: Fix C++11 build

Change-Id: Ib7dc8dcbeca7e85d97b8c7fb04d2cf42e5245298
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>