configure: Break single-line ac_config_files list into multiple lines.

[Saulius Krasuckas]

* On Sat, 24 Feb 2007, Marcus Meissner wrote:
> * On Sat, Feb 24, 2007 at 02:15:29PM +0200, Saulius Krasuckas wrote:
> > And I am not sure what stops us from keeping "ac_config_files" list 
> > multiline, so merging in future could be automatical.
> 
> The problem is that configure is automatically generated from 
> configure.ac.

Well, fair enough.  Can its generator be reconfigured then? :)