E0162 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0162.rs

Error E0162 needs a span_label, updating it from:

error[E0162]: irrefutable if-let pattern
  --> src/test/compile-fail/E0162.rs:15:12
   |
15 |     if let Irrefutable(x) = irr { //~ ERROR E0162
   |            ^^^^^^^^^^^^^^

To:

error[E0162]: irrefutable if-let pattern
  --> src/test/compile-fail/E0162.rs:15:12
   |
15 |     if let Irrefutable(x) = irr { //~ ERROR E0162
   |            ^^^^^^^^^^^^^^ irrefutable pattern