Migrate to cargo_embargo. am: 34065597a2

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/rustc-demangle-capi/+/2832426

Change-Id: I923deccee98783729b35ada74cafdc99d6fa804e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>