E0517 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0517.rs

E0517 needs a span_label, updating it from:

error[E0517]: attribute should be applied to struct or enum
  --> src/test/compile-fail/E0517.rs:11:1
   |
11 | #[repr(C)] //~ ERROR E0517
   | ^^^^^^^^^^

To:

error[E0517]: attribute should be applied to struct or enum
  --> src/test/compile-fail/E0517.rs:11:1
   |
11 | #[repr(C)] //~ ERROR E0517
   | ^^^^^^^^^^ requires a struct or enum

Note: you'll have to change the label to match title. There are a few different error examples in that file.