E0394 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0394.rs

E0394 needs a span_label, updated title, and a note, changing it from:

error[E0394]: cannot refer to other statics by value, use the address-of operator or a constant instead
  --> src/test/compile-fail/E0394.rs:12:17
   |
12 | static B: u32 = A; //~ ERROR E0394
   |                 ^

To:

error[E0394]: cannot refer to other statics by value
  --> src/test/compile-fail/E0394.rs:12:17
   |
12 | static B: u32 = A; //~ ERROR E0394
   |                 ^ referring to another static by value
   |
   = note: use the address-of operator or a constant instead