patch 9.1.1005: completion text is highlighted even with no pattern found

Problem:  completion text is highlighted even with no pattern found
Solution: use ins_compl_leader_len() instead of checking
          compl_leader.length (glepnir)

closes: #16422

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/insexpand.c b/src/insexpand.c
index 22f021d..4a02f0e 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -927,7 +927,7 @@
     if ((get_cot_flags() & COT_FUZZY))
 	return -1;
 
-    if (col >= (compl_col + (int)compl_leader.length) && col < compl_ins_end_col)
+    if (col >= (compl_col + (int)ins_compl_leader_len()) && col < compl_ins_end_col)
 	return syn_name2attr((char_u *)"ComplMatchIns");
 
     return -1;