libyang MAINTENANCE change format of the empty loops

To improve readability and because of processing by the formatting
tools, add explicit empty block to the empty loops (for, while).
diff --git a/src/parser_xml.c b/src/parser_xml.c
index 3bf8de0..5a4fb80 100644
--- a/src/parser_xml.c
+++ b/src/parser_xml.c
@@ -1021,7 +1021,7 @@
     if (op_p) {
         *op_p = rep_op;
     }
-    for (tree = rep_op; tree->parent; tree = LYD_PARENT(tree));
+    for (tree = rep_op; tree->parent; tree = LYD_PARENT(tree)) {}
     if (rpcr_e) {
         /* connect to the operation */
         lyd_insert_node(rpcr_e, NULL, tree);