Rename ddir_nr -> ddir_seq_nr

Another mode will be added, so lets rename this one internally
to make the distinction clear.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fio.h b/fio.h
index e05d95a..e9fdc68 100644
--- a/fio.h
+++ b/fio.h
@@ -146,7 +146,7 @@
 	char *ioengine;
 	enum td_ddir td_ddir;
 	unsigned int kb_base;
-	unsigned int ddir_nr;
+	unsigned int ddir_seq_nr;
 	unsigned int iodepth;
 	unsigned int iodepth_low;
 	unsigned int iodepth_batch;
@@ -410,7 +410,7 @@
 	os_random_state_t rwmix_state;
 	unsigned long rwmix_issues;
 	enum fio_ddir rwmix_ddir;
-	unsigned int ddir_nr;
+	unsigned int ddir_seq_nr;
 
 	/*
 	 * IO history logs for verification. We use a tree for sorting,