gfs: constify xattr_handler

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c
index 87ee309..9fb76b0 100644
--- a/fs/gfs2/acl.c
+++ b/fs/gfs2/acl.c
@@ -335,7 +335,7 @@
 	return error;
 }
 
-struct xattr_handler gfs2_xattr_system_handler = {
+const struct xattr_handler gfs2_xattr_system_handler = {
 	.prefix = XATTR_SYSTEM_PREFIX,
 	.flags  = GFS2_EATYPE_SYS,
 	.get    = gfs2_xattr_system_get,