Compare self with ROOT constant in is_root() method.

Author: Kixunil

src/unistd.rs

@@ -41,7 +41,7 @@ impl Uid {
 
     /// Returns true if the `Uid` represents privileged user - root. (If it equals zero.)
     pub fn is_root(&self) -> bool {
-        self.0 == 0
+        *self == ROOT
     }
 }