Add missing "product." prefix in GenericGCC module.

Change-Id: I96728e0919e596cb08da0eda4643c0894750fe9f
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Remove Artifact conditions in GenericGcc module.

The current implementation is bogus, and the "correct-looking way"
(using product.moduleProperty) does not work either.
This is another victim of QBS-370.

Change-Id: I5d7fa13def32ee4a8aee73755552505b1e9ab28d
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>