patch 8.2.3313: unused code in win_exchange() and frame_remove()

Problem:    Unused code in win_exchange() and frame_remove().
Solution:   Remove the code. (closes #8728)
diff --git a/src/version.c b/src/version.c
index a6e2f1e..db75af7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3313,
+/**/
     3312,
 /**/
     3311,