dmcompos/tests: Fix a failing test on Windows 8.

[Huw Davies]

On Fri, Feb 03, 2017 at 02:24:49PM +0100, Michael Stefaniuc wrote:
> On 02/03/2017 12:45 PM, Huw Davies wrote:
> > The dirty bit is most likely uninitialized, so sometimes this returns S_OK.
> Interesting, that seems to be only newtb-w8 that does that.

Yes.  FWIW, I tried calling IPersistStream_Save() in order to clear the
dirty bit, but that returned E_NOTIMPL on all Windows versions...

Huw.