tests/microbenchs/tasks_overhead.c: free allocated memory

tests/microbenchs/tasks_overhead.c

@@ -210,7 +210,7 @@ int main(int argc, char **argv)
         }
 
 	starpu_shutdown();
-
+	free(tasks);
 	return EXIT_SUCCESS;
 
 enodev:
@@ -218,5 +218,6 @@ enodev:
 	/* yes, we do not perform the computation but we did detect that no one
  	 * could perform the kernel, so this is not an error from StarPU */
 	starpu_shutdown();
+	free(tasks);
 	return STARPU_TEST_SKIPPED;
 }