patch 8.2.4389: screenpos() does not handle a position in a closed fold

Problem:    screenpos() does not handle a position in a closed fold.
Solution:   Check if the position is inside a closed fold. (closes #9778)
diff --git a/src/version.c b/src/version.c
index 559b602..7bf2ddb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4389,
+/**/
     4388,
 /**/
     4387,