void-variable evil-mode-buffers

Using evil `1.15.0` or `1.14.2` when I start emacs with evil I get this error message:

```
Error in post-command-hook (evil-normal-post-command): (void-variable evil-mode-buffers)
```

This var should be intitialized with:

```
(defvar evil-mode-buffers '())
```

This is error doesn't pop out using debug-mode, but it blocks my usage of magit. On master branch I don't see references to `evil-mode-buffers` so I assume this issue was fixed on it. It is still valuable to document the error in case others encounter it,

Can we cut a new release to fix it for everyone?

Thank you.

Start at the evil-normal-post-command hook and search the released 1.15.0/1.14.2 code and master branch for evil-mode-buffers. Confirm the startup error no longer occurs and that Magit remains usable, then determine what release steps are needed to make the fix available to users.

Written by the indexing model from the issue text.