[zxio] Call newly added zxio_destroy.

In fxr/359358, a new zxio function was introduced to decouple the
closing of connection from the closing of the client-end handle,
in order to resolve a race condition when closing zxio in the precense
of concurrent operations.

Change-Id: I206737e1b46d67fb253290da48de7e0d345a1d89
1 file changed