sm: request ack for every stanza

When stdin is closed with stream management enabled, xmppipe waits for
the ack to match the number of stanzas sent to ensure all the data has
been flushed to the server.

The server may not respond to every stream request and a stream request
message is generated only when a stanza is sent. Since stdin is closed,
the only traffic is the XMPP pings which are sent out every 60 seconds
by default. The result is, when stdin is closed, it may take several
minutes for xmppipe to exit.

Work around the problem by sending a stream management request for every
stanza.

src/xmppipe.c

@@ -72,7 +72,7 @@ main(int argc, char **argv)
     state->poll = 10;
     state->keepalive = 60 * 1000;
     state->keepalive_limit = 3;
-    state->sm_request_interval = 5;
+    state->sm_request_interval = 1;
 
     jid = xmppipe_getenv("XMPPIPE_USERNAME");
     pass = xmppipe_getenv("XMPPIPE_PASSWORD");