BUG/MINOR: error on unknown statement in ring section.

Previously unknown statements were silently ignored.
diff --git a/src/sink.c b/src/sink.c
index c65513a..50f0352 100644
--- a/src/sink.c
+++ b/src/sink.c
@@ -437,6 +437,11 @@
 			goto err;
 		}
 	}
+	else {
+		ha_alert("parsing [%s:%d] : unknown statement '%s'.\n", file, linenum, args[0]);
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto err;
+	}
 
 err:
 	return err_code;