Enable SIMD support for Windows on ARM

This enables SIMD support for Windows on ARM devices.

Patch submitted by Pierrick Bouvier <pierrick.bouvier@linaro.org>

Bug: https://github.com/flutter/flutter/issues/62597
Change-Id: I5480cb20f22fc14770df7bd6a305fdabe8755ef3
Reviewed-on: https://flutter-review.googlesource.com/c/third_party/libpng/+/34461
Commit-Queue: Chris Bracken <cbracken@google.com>
Reviewed-by: Jason Simmons <jsimmons@google.com>
Reviewed-by: Zach Anderson <zra@google.com>