Fix no_std build. am: fa8d2b59e5

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/virtio-drivers/+/2311751

Change-Id: Iaa11be912e2c95e57cd56baaa0785a4351949abd
Signed-off-by: Automerger Merge Worker <[email protected]>