The original test_compatibility_routines() only called
obj_to_primitive() without the version manifest, which means the fixture
could not be used to test compatibility routines on manifest backports.
This adds a kwarg to test_compatibility_routines() that allows users to
specify if they want to use the version manifest in the calls to
obj_to_primitive().
Change-Id: I1ef6eed1c79a2f2fc8967518a8a3d09e89ab64e3