patch 9.1.0147: Cannot keep a buffer focused in a window

Problem:  Cannot keep a buffer focused in a window
          (Amit Levy)
Solution: Add the 'winfixbuf' window-local option
          (Colin Kennedy)

fixes:  #6445
closes: #13903

Signed-off-by: Colin Kennedy <colinvfx@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/option.h b/src/option.h
index 75940cc..bf889e4 100644
--- a/src/option.h
+++ b/src/option.h
@@ -1309,6 +1309,7 @@
 #ifdef FEAT_STL_OPT
     , WV_STL
 #endif
+    , WV_WFB
     , WV_WFH
     , WV_WFW
     , WV_WRAP