Prevent statically linking to a lib providing stable C APIs

A lib providing stable C APIs should be available only to the APEX
containing the library. It shouldn't be available to other APEXes,
especially via static linking.

This change also fixes a bug that llndkImplDep (the dependency from
llndk stub to its implementation library) was recognized as being in the
same APEX.

Bug: 151051671
Test: m
Change-Id: Ifda7f4a367f68afcde93c86cda45a28cacd91f99