fcgi/client: don't allocate a new pool, operate on caller_pool
fcgi/client: don't allocate a new pool, operate on caller_pool

We don't need this anymore because the socket buffer has been moved
out of the pool.

CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy