Native ARM support for Cygwin

[Arthur Norman]

> I expect a crawling speed when running Cygwin in a ARM x86_64
> emulation mode
>
When I tried that a while ago on a macbook air m1 I was actually quite 
impressed. I ran windows-10-for-arm within UTM on the Mac. This was back 
in August and at that time ar least I had some misery with networking in 
the Windows world. Native ARM code runs with very little slowdown under 
Windows/UTM but what astonished me was that my own code running under 
cygwin-x86_64 in that world was maybe only a factor of 3 down on the same 
code native built on the Mac. So a slowdown but the Mac m1 is sufficiently 
fast that that is not really a crawl. I have not tried more recently and 
am concerned with rumours that Microsoft may withdraw x86_64 emulation 
from W10 (but keep it in W11), and with concerns about windows-for-arm 
licenses for use in a virtual environment.
Arthur