Be able to unselect the selected ABI when picking the ABIs to build

When you are picking the ABIs to build for in a project using Android, then the natural thing to do would be to move down the list. But if the first one is already selected then you have to select another one before you can unselect that. Ideally it would be possible to select/unselect at will and then if navigating away from the page means nothing is selected then it can reselect the default automatically.