make RangeInclusive Hash and !Copy

[breaking-change] due to the removal of Copy which shouldn't have been there in the first place, as per policy set forth in #27186.

src/libcore/ops.rs

@@ -1669,7 +1669,7 @@ impl<Idx: PartialOrd<Idx>> RangeTo<Idx> {
 ///     assert_eq!(arr[1...2], [  1,2  ]);  // RangeInclusive
 /// }
 /// ```
-#[derive(Copy, Clone, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq, Hash)]  // not Copy -- see #27186
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
 pub enum RangeInclusive<Idx> {
     /// Empty range (iteration has finished)