Make layout SizeOverflow test trigger on i686.

tests/compile-fail/repeat.rs

@@ -1,5 +1,5 @@
 fn main() {
-    let data: [u8; std::isize::MAX as usize] = [42; std::isize::MAX as usize];
+    let data: [u8; std::usize::MAX] = [42; std::usize::MAX];
     //~^ ERROR: rustc layout computation failed: SizeOverflow([u8;
     assert_eq!(data.len(), 1024);
 }