Revert "Remove unnecessary bailout in clif_pair_type_from_ty"

This reverts commit 3b22c3a.

Seems to be necessary after all. At least when compiling regex.

Author: bjorn3

src/common.rs

@@ -90,6 +90,9 @@ fn clif_pair_type_from_ty<'tcx>(
             let mut types = substs.types();
             let a = clif_type_from_ty(tcx, types.next().unwrap())?;
             let b = clif_type_from_ty(tcx, types.next().unwrap())?;
+            if a.is_vector() || b.is_vector() {
+                return None;
+            }
             (a, b)
         }
         ty::RawPtr(TypeAndMut { ty: pointee_ty, mutbl: _ }) | ty::Ref(_, pointee_ty, _) => {