Untangle the file creation mess

Still needs a lot of work, will do a rewrite of this soonish. At
least it should work now.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index cfbe378..6e9311b 100644
--- a/fio.h
+++ b/fio.h
@@ -692,6 +692,7 @@
 extern void get_file(struct fio_file *);
 extern void put_file(struct thread_data *, struct fio_file *);
 extern int add_dir_files(struct thread_data *, const char *);
+extern int init_random_map(struct thread_data *);
 
 /*
  * ETA/status stuff