Update D8 R8 to 8.4.16-dev am: 7a4d120031

Original change: https://android-review.googlesource.com/c/platform/prebuilts/r8/+/2981991

Change-Id: If605045efa2264fcc05a8211d35cd8d7205e29d7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>