Migrate to cargo_embargo. am: 4e010678ac am: d41ac629ad

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/num_cpus/+/2838081

Change-Id: I7a2d2f932b5abb6bbb7d891fd26c63a76337fdc4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>