Add build files for strum crate am: abadbccd53

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/strum/+/2924554

Change-Id: Ic930d9268db19d8688ee965543fd3e2081ff8526
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>