libyang CHANGE headers includes cleanup using include-what-you-use tool (#1098)

diff --git a/tests/utests/test_set.c b/tests/utests/test_set.c
index a4e4332..30a775d 100644
--- a/tests/utests/test_set.c
+++ b/tests/utests/test_set.c
@@ -11,15 +11,17 @@
  *
  *     https://opensource.org/licenses/BSD-3-Clause
  */
-#include "common.h"
+
+#define _GNU_SOURCE
 
 #include <stdarg.h>
 #include <stddef.h>
+#include <stdlib.h>
 #include <setjmp.h>
-#include <cmocka.h>
-
 #include <string.h>
 
+#include <cmocka.h>
+
 #include "../../src/set.h"
 
 #define BUFSIZE 1024