bug#21707: include-file cleanup for src directory

[Eli Zaretskii]

> From: Andy Moreton <andrewjmoreton@gmail.com>
> Date: Mon, 19 Oct 2015 13:54:15 +0100
> 
> > Would someone with MinGW64 installed please try this patch and see
> > that it works there as well?
> 
> I've done a full bootstrap without problems on MinGW64 from commit
> f1575763c0d3 with the patch and your additional fixes (which are needed
> on MinGW64 too).

Thanks.