Removed fixed fixme

Author: bonega

compiler/rustc_target/src/abi/mod.rs

@@ -1011,9 +1011,6 @@ impl Niche {
  let start = v.end.wrapping_add(1) & max_value;
  let end = v.end.wrapping_add(count) & max_value;
 
- // If the `end` of our range is inside the valid range,
- // then we ran out of invalid values.
- // FIXME(eddyb) abstract this with a wraparound range type.
  if v.contains(end) {
  return None;
  }