E0079 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0079.rs

Error E0079 needs a span_label, updating it from:

error[E0079]: mismatched types
  --> src/test/compile-fail/E0079.rs:12:9
   |
12 |     Q = "32" //~ ERROR E0079
   |         ^^^^
   |
   = note: expected type `isize`
   = note:    found type `string literal`

To:

error[E0079]: mismatched types
  --> src/test/compile-fail/E0079.rs:12:9
   |
12 |     Q = "32" //~ ERROR E0079
   |         ^^^^ expected `isize` type
   |
   = note: expected type `isize`
   = note:    found type `string literal`

[yossi-k]

On it