Upgrade rust/crates/which to 4.0.2 am: e92abd30fa am: 9b29c40588 am: ebb606a7fb

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/which/+/1388913

Change-Id: I28d3909de5abe779b83d345b7ccde0c7d59ac493