Fix multi source folder API checking

For libraries which have seperate source folders
per API level, the API generation doesn't currently
work correctly. When generating the stubs, we need to
input all source files, not just the final module.

This has uncovered some file in support-v4 which should
not be public API.

BUG: 20822048

Change-Id: I6216b9688e745db212959a07fcdc21bdd0aa5ab2
14 files changed