nit: use PathError when stat fails on normalize.

Signed-off-by: Manu Gupta <manugupt1@gmail.com>

mountinfo/mounted_unix.go

@@ -38,7 +38,7 @@ func normalizePath(path string) (realPath string, err error) {
 		return "", err
 	}
 	if _, err := os.Stat(realPath); err != nil {
-		return "", err
+		return "", &os.PathError{Op: "stat", Path: realPath, Err: err}
 	}
 	return realPath, nil
 }