[MINOR] prepare req_*/rsp_* to receive a condition

It will be very handy to be able to pass conditions to req_* and rsp_*.
For now, we just add the pointer to the condition in the affected
structs.
diff --git a/include/common/mini-clist.h b/include/common/mini-clist.h
index fa0537c..e89ffe0 100644
--- a/include/common/mini-clist.h
+++ b/include/common/mini-clist.h
@@ -39,6 +39,13 @@
 	char *s;
 };
 
+/* this is the same as above with an additional pointer to a condition. */
+struct cond_wordlist {
+	struct list list;
+	void *cond;
+	char *s;
+};
+
 /* First undefine some macros which happen to also be defined on OpenBSD,
  * in sys/queue.h, used by sys/event.h
  */