make const_err a hard error

src/test/ui/array-slice-vec/array_const_index-1.rs

@@ -1,8 +1,7 @@
 const A: [i32; 0] = [];
 const B: i32 = A[1];
 //~^ index out of bounds: the length is 0 but the index is 1
-//~| ERROR any use of this value will cause an error
-//~| WARN this was previously accepted by the compiler but is being phased out
+//~| ERROR evaluation of constant value failed
 
 fn main() {
     let _ = B;