Migrate to cargo_embargo. am: c2b6366a64 am: 0e019442e6 am: 80d5d415b1

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/bstr/+/2794737

Change-Id: I348a46141481f1433cce0ca8087940a0b340d464
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>