patch 8.2.4977: memory access error when substitute expression changes window

Problem:    Memory access error when substitute expression changes window.
Solution:   Disallow changing window in substitute expression.
diff --git a/src/version.c b/src/version.c
index 4c63ea0..782642b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4977,
+/**/
     4976,
 /**/
     4975,