[BUG] uri_auth: do not attemp to convert uri_auth -> http-request more than once

Bug reported by Laurent Dolosor.
diff --git a/include/common/uri_auth.h b/include/common/uri_auth.h
index a73c1ad..bffd694 100644
--- a/include/common/uri_auth.h
+++ b/include/common/uri_auth.h
@@ -30,6 +30,7 @@
 #define	ST_SHNODE	0x00000002	/* show node name */
 #define	ST_SHDESC	0x00000004	/* show description */
 #define	ST_SHLGNDS	0x00000008	/* show legends */
+#define	ST_CONVDONE	0x00000010	/* req_acl conversion done */
 
 /* later we may link them to support multiple URI matching */
 struct uri_auth {