Do not use '#endif/#else xxx'; it is not allowed for ANSI C

lang/m2/comp/error.c

@@ -72,7 +72,7 @@ debug(va_alist)
 	}
 	va_end(ap);
 }
-#endif DEBUG
+#endif /* DEBUG */
 
 /*VARARGS*/
 error(va_alist)
@@ -253,7 +253,7 @@ _error(class, node, ap)
 	case VDEBUG:
 		remark = "(debug)";
 		break;
-#endif DEBUG
+#endif /* DEBUG */
 	}
 	
 	/* the place */
@@ -268,7 +268,7 @@ _error(class, node, ap)
 	case FATAL:
 #ifdef DEBUG
 	case VDEBUG:
-#endif DEBUG
+#endif /* DEBUG */
 		ln = LineNumber;
 		break;
 	}