bug#5556: vc-next-action destroys window configuration

[martin rudalics]

> When doing vc-next-action, if the action is a commit, after you enter a
> commit message and commit your window configuration is destroyed.  An
> example of this is when you have one vertical split, created with C-x 3, and
> commit a file using this.  After the commit, you will only have one window.

I tried to address this together with bug#5310.

Thanks, martin