Refactor Project::targetExecutable().

We now implement this function in terms of targetArtifacts() and
installableFilesForProduct(), getting rid of redundancies.

Change-Id: Ie24b3bdd3381894500b67679fa4bb07268e952a0
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Fix autotest on OSX.

Prevent bundle creation.

Change-Id: I36eee6aeaac9c378d62f8ac700ca326d928cf488
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>