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/proto.h b/src/proto.h
index a5ca9e4..8282dc3 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -123,6 +123,9 @@
 # ifdef FEAT_VIMINFO
 #  include "viminfo.pro"
 # endif
+# ifdef FEAT_TABPANEL
+#  include "tabpanel.pro"
+# endif
 
 // These prototypes cannot be produced automatically.
 int smsg(const char *, ...) ATTRIBUTE_COLD ATTRIBUTE_FORMAT_PRINTF(1, 2);