E0438 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0438.rs

E0438 needs a span_label, updating it from:

error[E0438]: const `BAR` is not a member of trait `Foo`
  --> src/test/compile-fail/E0438.rs:16:5
   |
16 |     const BAR: bool = true; //~ ERROR E0438
   |     ^^^^^^^^^^^^^^^^^^^^^^^

To:

error[E0438]: const `BAR` is not a member of trait `Foo`
  --> src/test/compile-fail/E0438.rs:16:5
   |
16 |     const BAR: bool = true; //~ ERROR E0438
   |     ^^^^^^^^^^^^^^^^^^^^^^^ not a member of trait `Foo`

[bstrie]

Closed by #35858.