use thread_local for ntoa buf

@@ -1219,10 +1219,14 @@
                                 }
                                 if (strncmp(arg, "-xc99=%none", 11) == 0) {
                                         newae(ctx->i_ae, "-std=gnu89");
                                         break;
                                 }
+                                if (strncmp(arg, "-xc11=%all", 10) == 0) {
+                                        newae(ctx->i_ae, "-std=gnu11");
+                                        break;
+                                }
                                 if (strncmp(arg, "-xchip=", 7) == 0) {
                                         xlate(ctx->i_ae, arg + 7, xchip_tbl);
                                         break;
                                 }
                                 if (strncmp(arg, "-xcode=", 7) == 0) {