set CHANGE make ly_set* functions return LY_ERR values

unify ly_set* function that were returning -1 as error indicator
combined with positive value indicating index inside the set. The most
of other libyang functions return LY_ERR to indicate result. The problem
of these functions was also the limited range of the returned index.
While internally index is uint32_t, it was limited only to a positive
part of int type.
diff --git a/src/printer_lyb.c b/src/printer_lyb.c
index 1e4b145..0f5cf76 100644
--- a/src/printer_lyb.c
+++ b/src/printer_lyb.c
@@ -465,8 +465,7 @@
     const struct lyd_node *node;
     uint32_t i;
 
-    set = ly_set_new();
-    LY_CHECK_RET(!set, LY_EMEM);
+    LY_CHECK_RET(ly_set_new(&set));
 
     /* collect all data node modules */
     LY_LIST_FOR(root, node) {
@@ -475,14 +474,17 @@
         }
 
         mod = node->schema->module;
-        ly_set_add(set, mod, 0);
+        ret = ly_set_add(set, mod, 0, NULL);
+        LY_CHECK_GOTO(ret, cleanup);
 
         /* add also their modules deviating or augmenting them */
         LY_ARRAY_FOR(mod->compiled->deviated_by, u) {
-            ly_set_add(set, mod->compiled->deviated_by[u], 0);
+            ret = ly_set_add(set, mod->compiled->deviated_by[u], 0, NULL);
+            LY_CHECK_GOTO(ret, cleanup);
         }
         LY_ARRAY_FOR(mod->compiled->augmented_by, u) {
-            ly_set_add(set, mod->compiled->augmented_by[u], 0);
+            ret = ly_set_add(set, mod->compiled->augmented_by[u], 0, NULL);
+            LY_CHECK_GOTO(ret, cleanup);
         }
     }