Fixed more compiler warnings for unit tests

test/unit/lwip_unittests.c

@@ -10,8 +10,27 @@
 
 #include "lwip/init.h"
 
+Suite* create_suite(const char* name, testfunc *tests, size_t num_tests, SFun setup, SFun teardown)
+{
+  size_t i;
+  Suite *s = suite_create(name);
 
-int main()
+  for(i = 0; i < num_tests; i++) {
+    TCase *tc_core = tcase_create(name);
+    if ((setup != NULL) || (teardown != NULL)) {
+      tcase_add_checked_fixture(tc_core, setup, teardown);
+    }
+    tcase_add_named_test(tc_core, tests[i]);
+    suite_add_tcase(s, tc_core);
+  }
+  return s;
+}
+
+#ifdef LWIP_UNITTESTS_LIB
+int lwip_unittests_run(void)
+#else
+int main(void)
+#endif
 {
   int number_failed;
   SRunner *sr;