patch 9.1.0835: :setglobal doesn't work properly for 'ffu' and 'tsrfu'

Problem:  :setglobal doesn't work properly for 'ffu' and 'tsrfu' when
          the local value is set (after v9.1.0831)
Solution: Check os_flags instead of buffer option variable (zeertzjq).

closes: #15980

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 743a9e0..b39cf1e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    835,
+/**/
     834,
 /**/
     833,