bigfile/test: Don't forget to close opened RAM

Only one place that was using ram_new was missing to call ram_close in
the end.

bigfile/tests/test_ram.c

 /* Wendelin.bigfile | ram tests
- * Copyright (C) 2014-2015  Nexedi SA and Contributors.
+ * Copyright (C) 2014-2019  Nexedi SA and Contributors.
  *                          Kirill Smelkov <kirr@nexedi.com>
  *
  * This program is free software: you can Use, Study, Modify and Redistribute
@@ -147,6 +147,7 @@ int main()
 
 
     ramh_close(ramh);
+    ram_close(ram);
 
     return 0;
 }