[master] 84de64d typo

[Poul-Henning Kamp]

commit 84de64d5e4b463536957dc046f752da62a9b4180
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Wed Mar 4 13:08:31 2015 +0000

    typo

diff --git a/include/vtree.h b/include/vtree.h
index 04f551d..b88d9d2 100644
--- a/include/vtree.h
+++ b/include/vtree.h
@@ -31,7 +31,7 @@
 #define	_VTREE_H_
 
 #ifndef __unused
-define __unused __attribute__((__unused__))
+#define __unused __attribute__((__unused__))
 #endif
 
 /*