patch 8.2.3465: cannot detect insert scroll mode

Problem:    Cannot detect insert scroll mode.
Solution:   Add "scroll" to complete_info(). (closes #8943)
diff --git a/src/insexpand.c b/src/insexpand.c
index 0e363f7..ee8263c 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -68,7 +68,7 @@
 static char *ctrl_x_mode_names[] = {
 	"keyword",
 	"ctrl_x",
-	"unknown",	    // CTRL_X_SCROLL
+	"scroll",
 	"whole_line",
 	"files",
 	"tags",
@@ -2539,7 +2539,8 @@
     static char_u *
 ins_compl_mode(void)
 {
-    if (ctrl_x_mode == CTRL_X_NOT_DEFINED_YET || compl_started)
+    if (ctrl_x_mode == CTRL_X_NOT_DEFINED_YET || ctrl_x_mode == CTRL_X_SCROLL
+	    || compl_started)
 	return (char_u *)ctrl_x_mode_names[ctrl_x_mode & ~CTRL_X_WANT_IDENT];
 
     return (char_u *)"";