Rename DecorateLint as LintDiagnostic.

To match `derive(LintDiagnostic)`.

compiler/rustc_pattern_analysis/src/lints.rs

@@ -97,7 +97,7 @@ pub(crate) fn lint_nonexhaustive_missing_variants<'p, 'tcx>(
                     lint_name: "non_exhaustive_omitted_patterns",
                 };
 
-                use rustc_errors::DecorateLint;
+                use rustc_errors::LintDiagnostic;
                 let mut err = rcx.tcx.dcx().struct_span_warn(arm.pat.data().unwrap().span, "");
                 err.primary_message(decorator.msg());
                 decorator.decorate_lint(&mut err);