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/structs.h b/src/structs.h
index 5b88260..df2c005 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -246,6 +246,8 @@
     long	wo_nuw;
 # define w_p_nuw w_onebuf_opt.wo_nuw	// 'numberwidth'
 #endif
+    int wo_wfb;
+#define w_p_wfb w_onebuf_opt.wo_wfb	// 'winfixbuf'
     int		wo_wfh;
 # define w_p_wfh w_onebuf_opt.wo_wfh	// 'winfixheight'
     int		wo_wfw;