Add thread_options.h

The options are always problematic to merge between the master
repo and gfio. So import this bit from gfio.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/iolog.h b/iolog.h
index bb5c9b7..6a53de2 100644
--- a/iolog.h
+++ b/iolog.h
@@ -1,6 +1,7 @@
 #ifndef FIO_IOLOG_H
 #define FIO_IOLOG_H
 
+#include "rbtree.h"
 #include "lib/ieee754.h"
 
 /*
@@ -84,6 +85,7 @@
 	FIO_LOG_UNLINK_FILE,
 };
 
+struct io_u;
 extern int __must_check read_iolog_get(struct thread_data *, struct io_u *);
 extern void log_io_u(struct thread_data *, struct io_u *);
 extern void log_file(struct thread_data *, struct fio_file *, enum file_log_act);