Allow profiles to override internal io_u functions

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/init.c b/init.c
index acebb7d..a79bd1a 100644
--- a/init.c
+++ b/init.c
@@ -168,6 +168,8 @@
 	dup_files(td, parent);
 	options_mem_dupe(td);
 
+	profile_add_hooks(td);
+
 	td->thread_number = thread_number;
 	return td;
 }