Generate apex_available from c2a instead of a patch am: a2646fa4e4 am: b89935efef am: 07d2c381c9 am: d13c5afe1e

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/libm/+/1688571

Change-Id: I85f057aa901cd604ea48f6b27a18c69c726cd6bc