libadf is a new member of VNDK

The library is used by both platform (e.g. libminui) and vendors (for
theor HW composer HAL impl).

Bug: 64050301
Test: 2017 pixel devices build
Test: libadf.so is in /system/lib[64]/vndk directory
Change-Id: I20b8b9728cdc56a7491266070740c3330d4324dc