Migrate to cargo_embargo. am: 25ae9e30f0

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/fxhash/+/2822241

Change-Id: Ic43c0700e3a65e5b10a68188028c1385e3b2c4ed
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>