-rewrite_one_header(header_line *h, int flag, uschar *routed_old,
- uschar *routed_new, rewrite_rule *rewrite_rules, int existflags, BOOL replace)
+rewrite_one_header(header_line *h, int flag,
+ const uschar *routed_old, const uschar *routed_new,
+ rewrite_rule *rewrite_rules, int existflags, BOOL replace)