Use Symbol for the crate name instead of String/str

compiler/rustc_expand/src/base.rs

@@ -960,7 +960,7 @@ pub trait LintStoreExpand {
         node_id: NodeId,
         attrs: &[Attribute],
         items: &[P<Item>],
-        name: &str,
+        name: Symbol,
     );
 }
 

compiler/rustc_expand/src/expand.rs

@@ -1122,7 +1122,7 @@ impl InvocationCollectorNode for P<ast::Item> {
                         ecx.current_expansion.lint_node_id,
                         &attrs,
                         &items,
-                        ident.name.as_str(),
+                        ident.name,
                     );
                 }