patch 8.1.1457: cannot reuse a buffer when loading a screen dump

Problem:    Cannot reuse a buffer when loading a screen dump.
Solution:   Add the "bufnr" option.
diff --git a/src/version.c b/src/version.c
index 29006c1..f939ad8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -768,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1457,
+/**/
     1456,
 /**/
     1455,