ci: fix return value warning in test build code

Summary: this is a void function

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D10272

.ci/example/src/main.c

@@ -6,6 +6,6 @@
 EAPI_MAIN void
 efl_main(void *data EINA_UNUSED, const Efl_Event *ev EINA_UNUSED)
 {
-   return 0;
+   return;
 }
 EFL_MAIN()