Remove OatWriter::DexFileSource am: a8a815cb3a am: 51478e1584

Original change: https://android-review.googlesource.com/c/platform/art/+/2422726

Change-Id: I2a09347c183b13fda2aad00f4a165a02e4f81830
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>