E0261 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0261.rs

E0261 needs a span_label, updating it from:

error[E0261]: use of undeclared lifetime name `'a`
  --> src/test/compile-fail/E0261.rs:11:12
   |
11 | fn foo(x: &'a str) { } //~ ERROR E0261
   |            ^^

error[E0261]: use of undeclared lifetime name `'a`
  --> src/test/compile-fail/E0261.rs:14:9
   |
14 |     x: &'a str, //~ ERROR E0261
   |         ^^

To:

error[E0261]: use of undeclared lifetime name `'a`
  --> src/test/compile-fail/E0261.rs:11:12
   |
11 | fn foo(x: &'a str) { } //~ ERROR E0261
   |            ^^ undeclared lifetime

error[E0261]: use of undeclared lifetime name `'a`
  --> src/test/compile-fail/E0261.rs:14:9
   |
14 |     x: &'a str, //~ ERROR E0261
   |         ^^ undeclared lifetime

[creativcoder]

I'd like to work on it.