schema CHANGE remove private_destructor parameter from ly_ctx_destroy()

The mechanism was not reliable and not used often. libyang provide
function to traverse the schema and free the set data manually or the
caller can maintain some information to free the set data directly.

This commit changes API.
diff --git a/tests/utests/schema/test_parser_yin.c b/tests/utests/schema/test_parser_yin.c
index 7c726ff..c283570 100644
--- a/tests/utests/schema/test_parser_yin.c
+++ b/tests/utests/schema/test_parser_yin.c
@@ -158,7 +158,7 @@
 teardown_ctx(void **UNUSED(state))
 {
     lyxml_ctx_free(YCTX->xmlctx);
-    lys_module_free(YCTX->parsed_mod->mod, NULL);
+    lys_module_free(YCTX->parsed_mod->mod);
     free(YCTX);
     YCTX = NULL;
 
@@ -3422,7 +3422,7 @@
 {
     struct ly_ctx *ly_ctx = ctx->parsed_mod->mod->ctx;
 
-    lys_module_free(ctx->parsed_mod->mod, NULL);
+    lys_module_free(ctx->parsed_mod->mod);
     ctx->parsed_mod = calloc(1, sizeof *ctx->parsed_mod);
     ctx->parsed_mod->mod = calloc(1, sizeof *ctx->parsed_mod->mod);
     ctx->parsed_mod->mod->parsed = ctx->parsed_mod;
@@ -3550,7 +3550,7 @@
 {
     struct ly_ctx *ly_ctx = ctx->parsed_mod->mod->ctx;
 
-    lys_module_free(ctx->parsed_mod->mod, NULL);
+    lys_module_free(ctx->parsed_mod->mod);
     ctx->parsed_mod = calloc(1, sizeof(struct lysp_submodule));
     ctx->parsed_mod->mod = calloc(1, sizeof *ctx->parsed_mod->mod);
     lydict_insert(ly_ctx, belongs_to, 0, &ctx->parsed_mod->mod->name);
@@ -3710,7 +3710,7 @@
     assert_null(mod->parsed->exts->child->next->child);
     assert_string_equal(mod->parsed->exts->child->next->arg, "test");
     lys_compile_unres_glob_erase(UTEST_LYCTX, &unres);
-    lys_module_free(mod, NULL);
+    lys_module_free(mod);
     yin_parser_ctx_free(yin_ctx);
     ly_in_free(in, 0);
     mod = NULL;
@@ -3749,7 +3749,7 @@
     assert_int_equal(ly_in_new_memory(data, &in), LY_SUCCESS);
     assert_int_equal(yin_parse_module(&yin_ctx, in, mod, &unres), LY_SUCCESS);
     lys_compile_unres_glob_erase(UTEST_LYCTX, &unres);
-    lys_module_free(mod, NULL);
+    lys_module_free(mod);
     yin_parser_ctx_free(yin_ctx);
     ly_in_free(in, 0);
     mod = NULL;
@@ -3765,7 +3765,7 @@
     assert_int_equal(ly_in_new_memory(data, &in), LY_SUCCESS);
     assert_int_equal(yin_parse_module(&yin_ctx, in, mod, &unres), LY_SUCCESS);
     lys_compile_unres_glob_erase(UTEST_LYCTX, &unres);
-    lys_module_free(mod, NULL);
+    lys_module_free(mod);
     yin_parser_ctx_free(yin_ctx);
     ly_in_free(in, 0);
     mod = NULL;
@@ -3778,7 +3778,7 @@
     assert_int_equal(ly_in_new_memory(data, &in), LY_SUCCESS);
     assert_int_equal(yin_parse_module(&yin_ctx, in, mod, &unres), LY_EINVAL);
     CHECK_LOG_CTX("Input data contains submodule which cannot be parsed directly without its main module.", NULL);
-    lys_module_free(mod, NULL);
+    lys_module_free(mod);
     yin_parser_ctx_free(yin_ctx);
     ly_in_free(in, 0);
 
@@ -3793,7 +3793,7 @@
     assert_int_equal(ly_in_new_memory(data, &in), LY_SUCCESS);
     assert_int_equal(yin_parse_module(&yin_ctx, in, mod, &unres), LY_EVALID);
     CHECK_LOG_CTX("Trailing garbage \"<module>\" after module, expected end-of-input.", "Line number 6.");
-    lys_module_free(mod, NULL);
+    lys_module_free(mod);
     yin_parser_ctx_free(yin_ctx);
     ly_in_free(in, 0);
     mod = NULL;