Add lahfsahf and prfchw target feature

compiler/rustc_span/src/symbol.rs

@@ -932,6 +932,7 @@ symbols! {
         kreg0,
         label,
         label_break_value,
+        lahfsahf_target_feature,
         lang,
         lang_items,
         large_assignments,
@@ -1240,6 +1241,7 @@ symbols! {
         prelude,
         prelude_import,
         preserves_flags,
+        prfchw_target_feature,
         print_macro,
         println_macro,
         proc_dash_macro: "proc-macro",