E0050 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0050.rs

UPDATED: after a conversation on IRC, looks like the current thought is to update this:

error[E0050]: method `foo` has 1 parameter but the declaration in trait `Foo::foo` has 2
  --> src/test/compile-fail/E0050.rs:18:5
   |
18 |     fn foo(&self) -> bool { true } //~ ERROR E0050
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To:

error[E0050]: method `foo` has 3 parameters but the declaration in trait `Foo::foo` has 2
  --> src/test/compile-fail/E0050.rs:18:5
   |
12 |     fn foo(&self, x: u8) -> bool;
   |                   - trait requires 2 parameters
...
18 |     fn foo(&self, y: u8, z: u8) -> bool { true }
   |                          ^ 2 parameters expected, 3 found