Fixed crash due to uncancelled timer if there's an error in resolver's query transmit

[ming]

In ticket #1953:
Fail to create resolver when library built with IPv6 but run on system without IPv6

If the send count is zero, then transmit_query() will return PJLIB_UTIL_EDNSNOWORKINGNS, however it does so without cancelling the timer, which then will be put back in the list of free timer entries.

    status = transmit_query(resolver, q);
    if (status != PJ_SUCCESS) {
                pj_list_push_back(&resolver->query_free_nodes, q);
                goto on_return;
    }

Thus, it could later result in timer heap corruption and crash after this uncancelled timer is reused and invalidated.

Thanks to Chris Tserng for the fix and Balamurugan Ramajeyam for the report.

[ming]

In 5612:

Fixed #2024: Crash due to uncancelled timer if there's an error in resolver's query transmit