Fix startdelay option with s/m/h/d postfix

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fio.h b/fio.h
index bce81eb..e05d95a 100644
--- a/fio.h
+++ b/fio.h
@@ -208,7 +208,7 @@
 	unsigned int thinktime_blocks;
 	unsigned int fsync_blocks;
 	unsigned int fdatasync_blocks;
-	unsigned int start_delay;
+	unsigned long start_delay;
 	unsigned long long timeout;
 	unsigned long long ramp_time;
 	unsigned int overwrite;