Upgrade rust/crates/which to 4.1.0 am: d7bcf43786 am: b904996c6a am: 385a96330e am: 3f00182ae3

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/which/+/1662641

Change-Id: I9f44939ec21047471cce37b8613c512767bf8c8e