Migrate to cargo_embargo. am: 02ad4c1108

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/cexpr/+/2822396

Change-Id: Idb977d8e5f7d3df91d377b9c42789dca8f9e41a6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>