patch 9.1.0469: Cannot have buffer-local value for 'completeopt'

Problem:  Cannot have buffer-local value for 'completeopt'
          (Nick Jensen).
Solution: Make 'completeopt' global-local (zeertzjq).

Also for some reason test Test_ColonEight_MultiByte seems to be failing
sporadically now. Let's mark it as flaky.

fixes: #5487
closes: #14922

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/insexpand.pro b/src/proto/insexpand.pro
index 51f5db0..3d8c042 100644
--- a/src/proto/insexpand.pro
+++ b/src/proto/insexpand.pro
@@ -27,7 +27,7 @@
 int ins_compl_add_infercase(char_u *str_arg, int len, int icase, char_u *fname, int dir, int cont_s_ipos);
 int ins_compl_has_shown_match(void);
 int ins_compl_long_shown_match(void);
-void completeopt_was_set(void);
+unsigned get_cot_flags(void);
 int pum_wanted(void);
 void ins_compl_show_pum(void);
 char_u *find_word_start(char_u *ptr);