Merge "rust: Allow rustlibs to fallback to rlibs." am: 3736abfa01 am: b6289c9bbe

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2058050

Change-Id: Id6f3d23a321bd6be0235ea5ffcab018f054d1a5d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>