Use libraryInterface instead of concrete type asserts for stubs

Start consolidating stubs, llndk stubs, and ndk stubs by replacing
all of the concrete type asserts in the stubs methods with
libraryInterface.

Test: no change to build.ninja, Android-${TARGET_PRODUCT}.mk
Change-Id: I195d99c91e5f7afda5bcb489d20b524b3300c1b1