Runtime deps to a stubs lib crosses APEX boundary

When there is a runtime depedency (via runtime_libs property) to a
library providing stable C APIs, the dependency is considered as
crossing APEX boundary. Therefore, the requested lib doesn't need to be
made available to the APEX where the requesting lib is in.

Bug: 147813447
Test: m
Change-Id: I9cf8a5877850fb85b92c851e15fac921b8b7641b