try to make create_symlink platform-specific

src/tools/run-make-support/src/lib.rs

@@ -77,14 +77,17 @@ pub fn source_path() -> PathBuf {
 }
 
 /// Creates a new symlink to a path on the filesystem, adjusting for Windows or Unix.
+#[cfg(target_os = "windows")]
 pub fn create_symlink<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) {
-    if is_windows() {
-        use std::os::windows::fs;
-        fs::symlink_file(original, link).unwrap();
-    } else {
-        use std::os::unix::fs;
-        fs::symlink(original, link).unwrap();
-    }
+    use std::os::windows::fs;
+    fs::symlink_file(original, link).unwrap();
+}
+
+/// Creates a new symlink to a path on the filesystem, adjusting for Windows or Unix.
+#[cfg(target_os = "unix")]
+pub fn create_symlink<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) {
+    use std::os::unix::fs;
+    fs::symlink(original, link).unwrap();
 }
 
 /// Construct the static library name based on the platform.