Remove deny_warnings attribute am: 021dc75f2f am: 1bff1d5880 am: 4de6340660

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/log/+/1353763

Change-Id: Ic99f293aa99f93c76c8b4f87a787a2f6cc91821d