Add thread number ID to appropriate network commands

The client doesn't necessarily have a 1:1 mapping between jobs
and its internal job representation, so allow it to tell the
various jobs apart.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index db0e875..6e11754 100644
--- a/fio.h
+++ b/fio.h
@@ -66,8 +66,8 @@
 	void *eo;
 	char verror[FIO_VERROR_SIZE];
 	pthread_t thread;
-	int thread_number;
-	int groupid;
+	unsigned int thread_number;
+	unsigned int groupid;
 	struct thread_stat ts;
 
 	int client_type;