Proper API hierarchy between MODULE_LIBS and PRIV_APPS system APIs

Test: build / treehugger
Bug: 146727827
Exempt-From-Owner-Approval: Cherry-picking from goog/master to aosp/master
Merged-in: Ie1ad6711c490c679ebcfacd97154380a8810ba1c
Change-Id: Ie1ad6711c490c679ebcfacd97154380a8810ba1c
7 files changed