patch 8.2.4217: illegal memory access when undo makes Visual area invalid

Problem:    Illegal memory access when undo makes Visual area invalid.
Solution:   Correct the Visual area after undo.
diff --git a/src/version.c b/src/version.c
index f5f9a2e..6685b55 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4217,
+/**/
     4216,
 /**/
     4215,