Fix clippy tests

Author: estebank

src/tools/clippy/tests/ui/crashes/ice-6256.fixed

@@ -0,0 +1,15 @@
+// originally from rustc ./tests/ui/regions/issue-78262.rs
+// ICE: to get the signature of a closure, use args.as_closure().sig() not fn_sig()
+#![allow(clippy::upper_case_acronyms)]
+
+trait TT {}
+
+impl dyn TT + '_ {
+    fn func(&self) {}
+}
+
+#[rustfmt::skip]
+fn main() {
+    let f = |x: &dyn TT| x.func();
+    //~^ ERROR: borrowed data escapes outside of closure
+}

src/tools/clippy/tests/ui/crashes/ice-6256.stderr

@@ -8,6 +8,11 @@ LL |     let f = |x: &dyn TT| x.func();
    |              |  |        argument requires that `'1` must outlive `'static`
    |              |  let's call the lifetime of this reference `'1`
    |              `x` is a reference that is only valid in the closure body
+   |
+help: consider relaxing the implicit `'static` requirement on the impl
+   |
+LL | impl dyn TT + '_ {
+   |             ++++
 
 error: aborting due to 1 previous error