Update src/librustc_mir/interpret/terminator.rs

Co-Authored-By: Ralf Jung <post@ralfj.de>

Author: oli-obk

src/librustc_mir/interpret/terminator.rs

@@ -451,6 +451,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
  /// Evaluate a const function where all arguments (if any) are zero-sized types.
  /// The evaluation is memoized thanks to the query system.
+ // FIXME: Consider moving this to `const_eval.rs`.
  pub (crate) fn eval_const_fn_call(
  &mut self,
  gid: GlobalId<'tcx>,