Upgrade atomic to 0.6.0 am: 839041b30b am: ffc4a5b6cd

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/atomic/+/2939603

Change-Id: Ie5edcb80b5d537c9e8ed7de82c0e62f26b4b2218
Signed-off-by: Automerger Merge Worker <[email protected]>