BUG/MINOR: resolvers: Free new requester on error when linking a resolution

BUG/MINOR: resolvers: Free new requester on error when linking a resolution

If an error is triggered while the requester was allocated, it is not
immediately released. It is not really a memory leak because the requester
will be reused laster, on a next attempt, or released on deinit. For a
do-resolv action, the requester is released with the stream. So no leak
here. But it is probably not expected to keep a newly allocated requester in
case of error.

This patch could be backported as far as 2.6.