RFR: 8353009: Document target selection flag for Windows AArch64 builds

[Saint Wesonga]

On Mon, 31 Mar 2025 10:14:54 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> > Wait, are you saying you can get a native build to work by setting --build=aarch64-pc-cygwin? If so, then that's a better instruction IMO.
> 
> No, it's not. If we could block the `--build` flag, we would. This is the built-in autoconf target/host/build system, that messes with the structure we use in OpenJDK (since we do not do canadian cross builds).
> 
> So if you need to add configure option, this would be the correct one.
> 
> However, we should be able to figure this out by ourselves. This can be solved by a patch in `config.sub` and/or `config.guess`.

Thanks for the clarification that the --build flag is undesirable

-------------

PR Comment: https://git.openjdk.org/jdk/pull/24267#issuecomment-2766515715