Android 12.1.0 release 20
Generate apex_available from c2a instead of a patch am: b5eff22717 am: 131adf326c am: 8e459e84c0

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/futures-io/+/1688786

Change-Id: I9964dbc4b6567ef3dfaa14f4964643b6bda018c7