Do not assume type relationship when recording "not assignable"

The verifier may record that an interface I does not extend a
class A. If A is not j.l.Object, this is always true, but
A might change after a system update from a class to an interface.

bug: 34849974
test: verifier_deps_test
Change-Id: Ic2876edce9a2a6f7b402420a5e01763aba2b39a4