BUG/MINOR: http: add-header/set-header did not accept the ACL condition

Sander Klein reported this bug. The test for the extra argument on these
rules prevent any condition from being added. The bug was introduced with
the feature itself in 1.5-dev16.
diff --git a/src/proto_http.c b/src/proto_http.c
index ff71659..afb0db4 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -8130,7 +8130,8 @@
 		rule->action = *args[0] == 'a' ? HTTP_REQ_ACT_ADD_HDR : HTTP_REQ_ACT_SET_HDR;
 		cur_arg = 1;
 
-		if (!*args[cur_arg] || !*args[cur_arg+1] || *args[cur_arg+2]) {
+		if (!*args[cur_arg] || !*args[cur_arg+1] ||
+		    (*args[cur_arg+2] && strcmp(args[cur_arg+2], "if") != 0 && strcmp(args[cur_arg+2], "unless") != 0)) {
 			Alert("parsing [%s:%d]: 'http-request %s' expects exactly 2 arguments.\n",
 			      file, linenum, args[0]);
 			goto out_err;