Generate apex_available from c2a instead of a patch am: 80be90f058 am: e325c01929 am: ee1464a0c5 am: 8d89007260

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/futures-core/+/1688766

Change-Id: Ibbdb2b9f39e5bb62d85377de4b064ada006dc586