patch 9.1.0936: cannot highlight completed text

Problem:  cannot highlight completed text
Solution: (optionally) highlight auto-completed text using the
          ComplMatchIns highlight group (glepnir)

closes: #16173

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/insexpand.pro b/src/proto/insexpand.pro
index 4feab85..2e769b8 100644
--- a/src/proto/insexpand.pro
+++ b/src/proto/insexpand.pro
@@ -60,5 +60,6 @@
 void ins_compl_insert(int in_compl_func);
 void ins_compl_check_keys(int frequency, int in_compl_func);
 int ins_complete(int c, int enable_pum);
+int ins_compl_col_range_attr(int col);
 void free_insexpand_stuff(void);
 /* vim: set ft=c : */