Start of transition from unsigned long long to uint64_t

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/filesetup.c b/filesetup.c
index 4180909..b1ca921 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -709,7 +709,7 @@
 	return ret;
 }
 
-unsigned long long get_start_offset(struct thread_data *td)
+uint64_t get_start_offset(struct thread_data *td)
 {
 	return td->o.start_offset +
 		(td->thread_number - 1) * td->o.offset_increment;