Update clippy source code to make use of TyCtxt::def_descr instead of ItemKind::descr

Author: GuillaumeGomez

src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs

@@ -256,7 +256,10 @@ impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks {
                             cx,
                             UNNECESSARY_SAFETY_COMMENT,
                             span,
-                            format!("{} has unnecessary safety comment", item.kind.descr()),
+                            format!(
+                                "{} has unnecessary safety comment",
+                                cx.tcx.def_descr(item.owner_id.to_def_id()),
+                            ),
                             |diag| {
                                 diag.span_help(help_span, "consider removing the safety comment");
                             },
@@ -274,7 +277,10 @@ impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks {
                         cx,
                         UNNECESSARY_SAFETY_COMMENT,
                         span,
-                        format!("{} has unnecessary safety comment", item.kind.descr()),
+                        format!(
+                            "{} has unnecessary safety comment",
+                            cx.tcx.def_descr(item.owner_id.to_def_id()),
+                        ),
                         |diag| {
                             diag.span_help(help_span, "consider removing the safety comment");
                         },