Clippy: cfg out validate_diag on release builds

Author: flip1995

src/tools/clippy/clippy_utils/src/diagnostics.rs

@@ -38,6 +38,7 @@ fn docs_link(diag: &mut Diag<'_, ()>, lint: &'static Lint) {
 /// only started triggered there.
 ///
 /// This function makes sure we also validate them in debug clippy builds.
+#[cfg(debug_assertions)]
 fn validate_diag(diag: &Diag<'_, impl EmissionGuarantee>) {
     let suggestions = match &diag.suggestions {
         Suggestions::Enabled(suggs) => &**suggs,