vim: Import v8.1.2418

* 8.1.2418: bufnr('$') is wrong after recycling popup buffer
* 8.1.2417: MinGW/Cygwin build does not clean up all files
* 8.1.2416: loading menus sets v:errmsg
* 8.1.2415: popup menu flickers if an info popup is used

Author: chrisbra

gitlog.txt

@@ -1 +1 @@
-* Update a few runtime files.\n* [8.1.2414](https://github.com/vim/vim/releases/tag/v8.1.2414): MS-Windows: properties dialog box shows wrong character\n* [8.1.2413](https://github.com/vim/vim/releases/tag/v8.1.2413): cannot update ex_cmdidxs.h on MS-Windows
+* [8.1.2418](https://github.com/vim/vim/releases/tag/v8.1.2418): bufnr('$') is wrong after recycling popup buffer\n* [8.1.2417](https://github.com/vim/vim/releases/tag/v8.1.2417): MinGW/Cygwin build does not clean up all files\n* [8.1.2416](https://github.com/vim/vim/releases/tag/v8.1.2416): loading menus sets v:errmsg\n* [8.1.2415](https://github.com/vim/vim/releases/tag/v8.1.2415): popup menu flickers if an info popup is used