Pass the loop to MAKE_VALGRIND_HAPPY() so it's explicit on which loop
needs to be cleaned up. Since it asserts on uv_loop_close(), need to
remove a couple of those that were being done before the call.
Cleanup where loop was assigned, so the entire test either uses loop or
uv_default_loop(). Not both.
Also take care of any reqs that may have been left uncleaned.
Add UV_UDP_REUSEADDR flag instead, which can be passed to uv_udp_bind.
If the udp handle is unbound when uv_udp_set_memberhsip or
uv_udp_set_multicast_interface is called, the handle will be bound with
UV_UDP_REUSEADDR set.
