Add new net command for text logging

Encapsulate the text in a payload, that also includes the
logging level and the time the event took place. The text
client will do as it always has done, but the gui client
can now do proper logging and knows if this is debug/info
or error messages.

No functional change in the GUI.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/client.h b/client.h
index de6c197..7ab4c83 100644
--- a/client.h
+++ b/client.h
@@ -46,8 +46,7 @@
 	void *client_data;
 };
 
-typedef void (*client_text_op_func)(struct fio_client *client,
-		FILE *f, __u16 pdu_len, const char *buf);
+typedef void (*client_text_op_func)(struct fio_client *client, struct fio_net_cmd *cmd);
 typedef void (*client_disk_util_op_func)(struct fio_client *client, struct fio_net_cmd *cmd);
 typedef void (*client_thread_status_op)(struct fio_net_cmd *cmd);
 typedef void (*client_group_stats_op)(struct fio_net_cmd *cmd);