patch 9.1.1391: Vim does not have a vertical tabpanel

Problem:  Vim does not have a tabpanel
Solution: include the tabpanel feature
          (Naruhiko Nishino, thinca)

closes: #17263

Co-authored-by: thinca <thinca@gmail.com>
Signed-off-by: Naruhiko Nishino <naru123456789@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/optiondefs.h b/src/optiondefs.h
index f035104..d509463 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -305,7 +305,7 @@
 # define ISP_LATIN1 (char_u *)"@,161-255"
 #endif
 
-# define HIGHLIGHT_INIT "8:SpecialKey,~:EndOfBuffer,@:NonText,d:Directory,e:ErrorMsg,i:IncSearch,l:Search,y:CurSearch,m:MoreMsg,M:ModeMsg,n:LineNr,a:LineNrAbove,b:LineNrBelow,N:CursorLineNr,G:CursorLineSign,O:CursorLineFold,r:Question,s:StatusLine,S:StatusLineNC,c:VertSplit,t:Title,v:Visual,V:VisualNOS,w:WarningMsg,W:WildMenu,f:Folded,F:FoldColumn,A:DiffAdd,C:DiffChange,D:DiffDelete,T:DiffText,E:DiffTextAdd,>:SignColumn,-:Conceal,B:SpellBad,P:SpellCap,R:SpellRare,L:SpellLocal,+:Pmenu,=:PmenuSel,k:PmenuMatch,<:PmenuMatchSel,[:PmenuKind,]:PmenuKindSel,{:PmenuExtra,}:PmenuExtraSel,x:PmenuSbar,X:PmenuThumb,*:TabLine,#:TabLineSel,_:TabLineFill,!:CursorColumn,.:CursorLine,o:ColorColumn,q:QuickFixLine,z:StatusLineTerm,Z:StatusLineTermNC,g:MsgArea,h:ComplMatchIns"
+# define HIGHLIGHT_INIT "8:SpecialKey,~:EndOfBuffer,@:NonText,d:Directory,e:ErrorMsg,i:IncSearch,l:Search,y:CurSearch,m:MoreMsg,M:ModeMsg,n:LineNr,a:LineNrAbove,b:LineNrBelow,N:CursorLineNr,G:CursorLineSign,O:CursorLineFold,r:Question,s:StatusLine,S:StatusLineNC,c:VertSplit,t:Title,v:Visual,V:VisualNOS,w:WarningMsg,W:WildMenu,f:Folded,F:FoldColumn,A:DiffAdd,C:DiffChange,D:DiffDelete,T:DiffText,E:DiffTextAdd,>:SignColumn,-:Conceal,B:SpellBad,P:SpellCap,R:SpellRare,L:SpellLocal,+:Pmenu,=:PmenuSel,k:PmenuMatch,<:PmenuMatchSel,[:PmenuKind,]:PmenuKindSel,{:PmenuExtra,}:PmenuExtraSel,x:PmenuSbar,X:PmenuThumb,*:TabLine,#:TabLineSel,_:TabLineFill,!:CursorColumn,.:CursorLine,o:ColorColumn,q:QuickFixLine,z:StatusLineTerm,Z:StatusLineTermNC,g:MsgArea,h:ComplMatchIns,%:TabPanel,^:TabPanelSel,&:TabPanelFill"
 
 // Default python version for pyx* commands
 #if defined(FEAT_PYTHON) && defined(FEAT_PYTHON3)
@@ -2368,6 +2368,11 @@
     {"showtabline", "stal", P_NUM|P_VI_DEF|P_RALL,
 			    (char_u *)&p_stal, PV_NONE, did_set_showtabline, NULL,
 			    {(char_u *)1L, (char_u *)0L} SCTX_INIT},
+#if defined(FEAT_TABPANEL)
+    {"showtabpanel", "stpl", P_NUM|P_RALL,
+			    (char_u *)&p_stpl, PV_NONE, did_set_showtabpanel, NULL,
+			    {(char_u *)0L, (char_u *)0L} SCTX_INIT},
+#endif
     {"sidescroll",  "ss",   P_NUM|P_VI_DEF,
 			    (char_u *)&p_ss, PV_NONE, NULL, NULL,
 			    {(char_u *)0L, (char_u *)0L} SCTX_INIT},
@@ -2527,6 +2532,16 @@
     {"tabpagemax",  "tpm",  P_NUM|P_VI_DEF,
 			    (char_u *)&p_tpm, PV_NONE, NULL, NULL,
 			    {(char_u *)10L, (char_u *)0L} SCTX_INIT},
+#if defined(FEAT_TABPANEL)
+    {"tabpanel",  "tpl",    P_STRING|P_VI_DEF|P_RALL,
+			    (char_u *)&p_tpl, PV_NONE, NULL, NULL,
+			    {(char_u *)"", (char_u *)0L} SCTX_INIT},
+    {"tabpanelopt","tplo",  P_STRING|P_VI_DEF|P_ONECOMMA|P_NODUP,
+			    (char_u *)&p_tplo, PV_NONE, did_set_tabpanelopt,
+			    expand_set_tabpanelopt,
+			    {(char_u *)"", (char_u *)0L}
+			    SCTX_INIT},
+#endif
     {"tabstop",	    "ts",   P_NUM|P_VI_DEF|P_RBUF,
 			    (char_u *)&p_ts, PV_TS,
 			    did_set_shiftwidth_tabstop, NULL,