[patch testsuite]: Deactivate some test in gfortran.dg not supported by w64

[Tobias Burnus]

Kai Tietz wrote:
> Do you mean I should deactivate it for all mingw targets? I did this here 
> just for the x86_64 version.
>   
I expect that it also fails for the other mingw versions as I believe 
"chmod" is not supported, but frankly, I do not know. It would be great 
if you could test it. (I cannot I have no working Windows around.)

Tobias