Merge changes I0527ef62,I0d66a93f,I528ef380,Ia9140851,If1874867, ...

* changes:
  vndk-def: Fix bad inward-customized vndk calculation.
  vndk-def: Fix inward customization.
  vndk-def: Rename vndk-core and vndk-ext libs.
  vndk-def: Rename map_path_to_lib(s) to get_lib(s).
  vndk-def: Rename ELFLinker.add() to add_lib().
  vndk-def: Add non-AOSP lib to imported_ext_symbols.
  vndk-def: Skip ndk ext check if no generic-refs.