tests: Fix leak of input event & devices

After the previous patch, the caller of efl_input_dup() clearly owns the
reference on the returned object, which means she must absolutely delete
or unref if manually.

Note that the previous patch changed the bug from use of invalid eo
pointer to leaking of objects. But the only way to support bindings with
something like dup() is to ensure we give a ref to the caller, and thus
the parent should be null.

Note: eo_debug was used extensively to reach this point.

src/bin/elementary/test_events.c

@@ -142,6 +142,11 @@ static void
 _win_del(void *data, const Efl_Event *ev EINA_UNUSED)
 {
    testdata *td = data;
+   efl_del(td->evdown);
+   efl_del(td->evup);
+   efl_del(td->evmove);
+   efl_del(td->evkeydown);
+   efl_del(td->evkeyup);
    free(td);
 }