BUG/MINOR: mux-h1: Enable keep-alive on server side

Don't force the close on server side anymore. Since commit 7c6f8b146 ("MAJOR:
connections: Detach connections from streams"), it is possible to release a
stream without the underlying connection.

Because of this change, we must be sure to create a new stream to handle the
next HTTP transaction only on the client side. And we must be sure to correctly
handle the read0 event in h1_recv, to be sure to call h1_process().
1 file changed