Fix invalid free when destroying pools created with
apr_pool_create_unmanaged_ex()

PR: 54892
Submitted by: Valeriy V. Argunov <hzdbyte gmail com>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1478934 13f79535-47bb-0310-9956-ffa450edef68