winex11.drv: Send WM_DROPFILES if IDropTarget_Drop failed

[Piotr Caban]

On 11/20/15 08:45, Piotr Caban wrote:
> This partially fixes following regression:
> https://bugs.winehq.org/show_bug.cgi?id=39445
> unfortunately there's another regression caused by
> 3f99e71fde8231524597901e512e5c1909a82e1e commit in this application.
>
Please ignore this patch for now, I'll send a more complete solution for 
bug 39445.

Thanks,
Piotr