Generate apex_available from c2a instead of a patch am: 9d0e2785f6 am: a2a05c87b5 am: 0fc74f4358 am: c39d4b91e5

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/proc-macro-nested/+/1689358

Change-Id: Ia0d836485ac51a071c5b584c36484e14ef45f291