Fix ldmsd_stream_subscribe intermingled events output

Multiple threads in `ldmsd_stream_subscribe` can race to handle stream
recv events. The recv handler called `msglog()` multiple times to print
out the EVENT. This lead to intermingled events in the output. This
patch modifies the handler to print the events in single msglog call to
avoid the intermingled output.

ldms/src/ldmsd/test/ldmsd_stream_subscribe.c

@@ -165,16 +165,13 @@ static int stream_unsubscribe_status_ev(ldms_stream_event_t ev, void *arg)
 
 static int stream_recv_ev(ldms_stream_event_t ev, void *arg)
 {
-	if (!events_raw) {
-		if (ev->recv.type == LDMS_STREAM_STRING)
-			msglog("EVENT:{\"type\":\"string\",\"size\":%d,\"event\":", ev->recv.data_len);
-		else
-			msglog("EVENT:{\"type\":\"json\",\"size\":%d,\"event\":", ev->recv.data_len);
+	if (events_raw) {
+		msglog("%s\n", ev->recv.data);
+		return 0;
 	}
-	msglog(ev->recv.data);
-	if (!events_raw)
-		msglog("}");
-	msglog("\n");
+	msglog("EVENT:{\"type\":\"%s\",\"size\":%d,\"event\":%s}\n",
+			LDMS_STREAM_STRING ? "string" : "json",
+			ev->recv.data_len, ev->recv.data);
 	return 0;
 }