In THD::cleanup(), apc_target.destroy() has assertion failure.

In sql/sql_class.cc, THD::cleanup() calls apc_target.destroy().

The latter has:
DBUG_ASSERT(!enabled) which fails during our test which triggers this code path.

The fix is to disable apc_target if it is enabled before destroying it.

Proposed patch:

void THD::cleanup(void)

{

...

  DBUG_ASSERT(!mdl_context.has_locks());

+  if (apc_target.is_enabled())

+    apc_target.disable();

  apc_target.destroy();

...

}