message: Unignore some more libcore tests
diff: @@ -38,31 +38,15 @@ index c9096b7..be37fcd 100644
  }
  #[test]
  -+#[ignore]
  ++#[ignore] // checked_mul impl not yet checking for overflow
  fn test_iterator_step_by_nth_overflow() {
  #[cfg(target_pointer_width = "8")]
  type Bigger = u16;
  -@@ -2184,6 +2185,7 @@ fn test_range_inclusive_folds() {
  - }
  -
  - #[test]
  -+#[ignore]
  - fn test_range_size_hint() {
  - assert_eq!((0..0usize).size_hint(), (0, Some(0)));
  - assert_eq!((0..100usize).size_hint(), (100, Some(100)));
  -@@ -2210,6 +2212,7 @@ fn test_range_size_hint() {
  - }
  -
  - #[test]
  -+#[ignore]
  - fn test_range_inclusive_size_hint() {
  - assert_eq!((1..=0usize).size_hint(), (0, Some(0)));
  - assert_eq!((0..=0usize).size_hint(), (1, Some(1)));
  @@ -2305,6 +2308,7 @@ fn test_repeat_with_take_collect() {
  }
  #[test]
  -+#[ignore]
  ++#[ignore] // checked_mul impl not yet checking for overflow
  fn test_successors() {
  let mut powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10));
  assert_eq!(powers_of_10.by_ref().collect::<Vec<_>>(), &[1, 10, 100, 1_000, 10_000]);
  @@ -74,7 +58,7 @@ index a17c094..5bb11d2 100644
  }
  #[test]
  -+#[ignore]
  ++#[ignore] // checked_mul impl not yet checking for overflow
  fn from_str_issue7588() {
  let u: Option<u8> = u8::from_str_radix("1000", 10).ok();
  assert_eq!(u, None);
  @@ -102,7 +86,7 @@ index fac70c4..9107a02 100644
  }
  #[test]
  -+#[ignore]
  ++#[ignore] // checked_mul impl not yet checking for overflow
  fn checked_mul() {
  assert_eq!(Duration::new(0, 1).checked_mul(2), Some(Duration::new(0, 2)));
  assert_eq!(Duration::new(1, 1).checked_mul(3), Some(Duration::new(3, 3)));
  