Do not rebuild the build script unless necessary

Without this guard, the build script is rebuilt as soon as any file
within the package is changed. This includes files created by external
tools such as IDE.

build.rs

@@ -15,6 +15,10 @@ pub fn main() {
     const FEATURE_PREFIX: &str = "feat_";
     const OVERRIDE_PREFIX: &str = "uu_";
 
+    // Do not rebuild build script unless the script itself or the enabled features are modified
+    // See <https://doc.rust-lang.org/cargo/reference/build-scripts.html#change-detection>
+    println!("cargo:rerun-if-changed=build.rs");
+
     if let Ok(profile) = env::var("PROFILE") {
         println!("cargo:rustc-cfg=build={profile:?}");
     }