Vendor things

third-party/vendor/which/README.md

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+[![Build Status](https://github.com/harryfei/which-rs/actions/workflows/rust.yml/badge.svg)](https://github.com/harryfei/which-rs/actions/workflows/rust.yml)
+
+# which
+
+A Rust equivalent of Unix command "which". Locate installed executable in cross platforms.
+
+## Support platforms
+
+* Linux
+* Windows
+* macOS
+
+## Examples
+
+1) To find which rustc executable binary is using.
+
+    ``` rust
+    use which::which;
+
+    let result = which("rustc").unwrap();
+    assert_eq!(result, PathBuf::from("/usr/bin/rustc"));
+    ```
+
+2. After enabling the `regex` feature, find all cargo subcommand executables on the path:
+
+    ``` rust
+    use which::which_re;
+
+    which_re(Regex::new("^cargo-.*").unwrap()).unwrap()
+        .for_each(|pth| println!("{}", pth.to_string_lossy()));
+    ```
+
+## MSRV
+
+This crate currently has an MSRV of Rust 1.63. Increasing the MSRV is considered a breaking change and thus requires a major version bump.
+
+## Documentation
+
+The documentation is [available online](https://docs.rs/which/).