Migrate to cargo_embargo. am: 8db550a9e9 am: 5c4eeb65ff am: 24c208e178

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/threadpool/+/2828054

Change-Id: I5600bc224f0bbb7d0b8a0ea3d33935b8b49136a2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>