patch 8.2.4568: getmousepos() does not compute the column below the last line

Problem:    getmousepos() does not compute the column below the last line.
Solution:   Also compute the column when the mouse is below the last line.
            (Sean Dewar, closes #9946)
diff --git a/src/version.c b/src/version.c
index 4a4aa75..c4a65f3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4568,
+/**/
     4567,
 /**/
     4566,