Generate apex_available from c2a instead of a patch am: 60e7e48668 am: a1d5e4e693 am: 1c2a7f36dd

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/futures-executor/+/1688785

Change-Id: I6ad892e22eac0a1d784edaa940f75b68da66271b