qtprofilesetup: Fix minimum OS X version setting.

We have to check QT_CONFIG, not CONFIG.

Change-Id: I512e1e1c78107b7fa1d2d4d88b79997a14bf3021
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
Fix property look-up.

We must not stop searching for the property just because the respective
module is present in the product; the property itself must have been
found as well.

Change-Id: Icc4fb019094909f1da26d649dcbe54d76a09f2d0
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>