num2str: add arguments to represent values in terms of bytes/bits

This allows for representing I/O rates in terms of e.g. megabits (Mb) versus
megabytes (MB).

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index db594ab..cc43976 100644
--- a/fio.h
+++ b/fio.h
@@ -686,7 +686,7 @@
 extern void options_mem_dupe(void *data, struct fio_option *options);
 extern void td_fill_rand_seeds(struct thread_data *);
 extern void add_job_opts(const char **);
-extern char *num2str(unsigned long, int, int, int);
+extern char *num2str(unsigned long, int, int, int, int);
 extern int ioengine_load(struct thread_data *);
 
 #define FIO_GETOPT_JOB		0x89000000