patch 9.0.0824: crash when using win_move_separator() in other tab page

Problem:    Crash when using win_move_separator() in other tab page.
Solution:   Check for valid window in current tab page.
            (closes #11479, closes #11427)
diff --git a/src/version.c b/src/version.c
index 16054b0..5d1a2fb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    824,
+/**/
     823,
 /**/
     822,