Make flagset available to product and vendor am: a3ab55c917 am: 1a67c9ff61 am: 9f18840d2d am: 4f06d9dd1d

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/flagset/+/2476404

Change-Id: I6c811ad606bb2a77e467a411910463ef406fbaca
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>