bug#21173: 25.0.50; New frames positioned off screen with multiple monitors

[martin rudalics]

> The patch below fixes the problem for me on a Mingw64 build, and creates
> frames at the correct position.  Please try it and report the results.
>
> (Copyright papers are not yet on file, but I mailed them today).

Andy informed us that his copyright papers are now on file so we can
install this patch.

Francis, did you try the patch?  If not, pretty please do.

Also, did anyone see a similar problem on X or anywhere else?  I don't
use multiple monitors and am not eager to simluate them.

Thanks for responses, martin