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/optiondefs.h b/src/optiondefs.h
index 1a09e1c..4ee2e20 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -215,6 +215,7 @@
 # define PV_STL		OPT_BOTH(OPT_WIN(WV_STL))
 #endif
 #define PV_UL		OPT_BOTH(OPT_BUF(BV_UL))
+# define PV_WFB		OPT_WIN(WV_WFB)
 # define PV_WFH		OPT_WIN(WV_WFH)
 # define PV_WFW		OPT_WIN(WV_WFW)
 #define PV_WRAP		OPT_WIN(WV_WRAP)
@@ -2850,6 +2851,9 @@
     {"window",	    "wi",   P_NUM|P_VI_DEF,
 			    (char_u *)&p_window, PV_NONE, did_set_window, NULL,
 			    {(char_u *)0L, (char_u *)0L} SCTX_INIT},
+    {"winfixbuf", "wfb", P_BOOL|P_VI_DEF|P_RWIN,
+			    (char_u *)VAR_WIN, PV_WFB, NULL, NULL,
+			    {(char_u *)FALSE, (char_u *)0L} SCTX_INIT},
     {"winfixheight", "wfh", P_BOOL|P_VI_DEF|P_RSTAT,
 			    (char_u *)VAR_WIN, PV_WFH, NULL, NULL,
 			    {(char_u *)FALSE, (char_u *)0L} SCTX_INIT},