[m-rev.] diff: Support llvm-mingw targets in configure_cross.

[Julien Fischer]

On Fri, 8 Aug 2025 at 16:07, Peter Wang <novalazy at gmail.com> wrote:
>
> tools/configure_cross:
>     Include config values for llvm-mingw (clang) compilers
>     targeting Windows/x86-64 and Windows/ARM64.

Does the x86_64 one work?  I've never had much luck getting
a working Mercury compiler with it on Windows.

Julien.