Fix WiX autotest.

Change-Id: I2b52a0ef469fd3faa036556babed20300837606d
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Fix "Add Files" functionality.

This was broken for the case of a product with no existing binding, even
accessing a null pointer. This is also covered by the autotest now.

Change-Id: I088dbac08627b08f903dbe77bd824997592adb09
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Properly treat "usings" as inputs when applying rules.

This allows non-multiplex rules with only "usings" and no "inputs" to
work as expected, that is they create one transformer per "usings"
element.

Change-Id: Iba5144f81b082043878f3eefc111846b6d05646a
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>