tests/datawizard/lazy_unregister.c: include unistd.h for usleep

tests/datawizard/lazy_unregister.c

@@ -17,6 +17,7 @@
 #include <config.h>
 #include <starpu.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include "../helper.h"