Reference libcore, conscrypt and icu sources directly

Avoids an extra aggregation step in the creation of the API sources.

Bug: 153306490
Test: m nothing
Bug: 142935992
Merged-In: Ia15c3ceb9fc59e7945687536c60ce265ec95781e
Change-Id: Ia15c3ceb9fc59e7945687536c60ce265ec95781e
(cherry picked from commit 5c89e70a1fbbc9f9251342358835c8a139eb2285)
2 files changed