BUG/MINOR: to_log erased with unique-id-format

curproxy->to_log was reset to LW_INIT when using unique-id-format,
so logs looked like option logasap
diff --git a/src/log.c b/src/log.c
index 2a3cd16..b1f532a 100644
--- a/src/log.c
+++ b/src/log.c
@@ -309,7 +309,7 @@
 	struct logformat_node *tmplf, *back;
 	int options = 0;
 
-	curproxy->to_log = LW_INIT;
+	curproxy->to_log |= LW_INIT;
 
 	/* flush the list first. */
 	list_for_each_entry_safe(tmplf, back, list_format, list) {