Constify

found by flexelint

bin/varnishd/cache/cache_varnishd.h

@@ -462,7 +462,7 @@ void VCP_Panic(struct vsb *, struct conn_pool *);
 
 /* cache_vary.c */
 int VRY_Create(struct busyobj *bo, struct vsb **psb);
-int VRY_Match(struct req *, const uint8_t *vary);
+int VRY_Match(const struct req *, const uint8_t *vary);
 void VRY_Prep(struct req *);
 void VRY_Clear(struct req *);
 enum vry_finish_flag { KEEP, DISCARD };

bin/varnishd/cache/cache_vary.c

@@ -286,7 +286,7 @@ VRY_Finish(struct req *req, enum vry_finish_flag flg)
  */
 
 int
-VRY_Match(struct req *req, const uint8_t *vary)
+VRY_Match(const struct req *req, const uint8_t *vary)
 {
 	uint8_t *vsp = req->vary_b;
 	const char *h, *e;