Add 'ifndef/endif' to avoid conflict of 'TRUE' definition.

src/parse.y

@@ -41,8 +41,13 @@ static void backref_error(parser_state *p, node *n);
 
 #define identchar(c) (isalnum(c) || (c) == '_' || !isascii(c))
 
+#ifndef TRUE
 #define TRUE  1
+#endif
+
+#ifndef FALSE
 #define FALSE 0
+#endif
 
 typedef unsigned int stack_type;