Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/READMEdir/README_os390.txt b/READMEdir/README_os390.txt
index 0b0ec9a..24c668c 100644
--- a/READMEdir/README_os390.txt
+++ b/READMEdir/README_os390.txt
@@ -1,4 +1,4 @@
-README_zOS.txt for version 8.0 of Vim: Vi IMproved.
+README_zOS.txt for version 8.1 of Vim: Vi IMproved.
 
 This readme explains how to build Vim on z/OS.  Formerly called OS/390.
 See "README.txt" for general information about Vim.