Add support for registrering external options

Start of support for real profiles.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/options.h b/options.h
new file mode 100644
index 0000000..29bb7a1
--- /dev/null
+++ b/options.h
@@ -0,0 +1,16 @@
+#ifndef FIO_OPTION_H
+#define FIO_OPTION_H
+
+#include "parse.h"
+#include "flist.h"
+
+#define td_var_offset(var)	((size_t) &((struct thread_options *)0)->var)
+
+struct ext_option {
+	struct flist_head list;
+	struct fio_option o;
+};
+
+void register_option(struct ext_option *);
+
+#endif