Allow const_err in out_of_bounds_indexing tests

Author: Manishearth

tests/ui/out_of_bounds_indexing/empty_array.rs

@@ -1,5 +1,5 @@
 #![warn(clippy::out_of_bounds_indexing)]
-#![allow(clippy::no_effect, clippy::unnecessary_operation)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation, const_err)]
 
 fn main() {
     let empty: [i8; 0] = [];

tests/ui/out_of_bounds_indexing/empty_array.stderr

@@ -1,11 +1,3 @@
-error: index out of bounds: the len is 0 but the index is 0
-  --> $DIR/empty_array.rs:6:5
-   |
-LL |     empty[0];
-   |     ^^^^^^^^
-   |
-   = note: `#[deny(const_err)]` on by default
-
 error: range is out of bounds
   --> $DIR/empty_array.rs:7:12
    |
@@ -50,5 +42,5 @@ error: range is out of bounds
 LL |     &empty[..=0];
    |               ^
 
-error: aborting due to 8 previous errors
+error: aborting due to 7 previous errors
 

tests/ui/out_of_bounds_indexing/issue-3102.rs

@@ -1,5 +1,5 @@
 #![warn(clippy::out_of_bounds_indexing)]
-#![allow(clippy::no_effect)]
+#![allow(clippy::no_effect, const_err)]
 
 fn main() {
     let x = [1, 2, 3, 4];

tests/ui/out_of_bounds_indexing/simple.rs

@@ -1,5 +1,5 @@
 #![warn(clippy::out_of_bounds_indexing)]
-#![allow(clippy::no_effect, clippy::unnecessary_operation)]
+#![allow(clippy::no_effect, clippy::unnecessary_operation, const_err)]
 
 fn main() {
     let x = [1, 2, 3, 4];