Add feature and attribute definition

compiler/rustc_span/src/symbol.rs

@@ -656,6 +656,7 @@ symbols! {
         dyn_trait,
         e,
         edition_panic,
+        effects,
         eh_catch_typeinfo,
         eh_personality,
         emit,
@@ -793,6 +794,7 @@ symbols! {
         hexagon_target_feature,
         hidden,
         homogeneous_aggregate,
+        host,
         html_favicon_url,
         html_logo_url,
         html_no_source,
@@ -1284,6 +1286,7 @@ symbols! {
         rustc_evaluate_where_clauses,
         rustc_expected_cgu_reuse,
         rustc_has_incoherent_inherent_impls,
+        rustc_host,
         rustc_if_this_changed,
         rustc_inherit_overflow_checks,
         rustc_insignificant_dtor,