Official support for windows-arm64

[Pierrick Bouvier]

Dear LibreOffice developers,

I would like to discuss and offer some help on support for windows-arm64 
platform.

Linaro, through the Windows on Arm 
(https://www.linaro.org/windows-on-arm/) team, has been supporting 
various open source projects to enable them on windows-arm64. In 
collaboration with Microsoft, we would like to help LibreOffice to offer 
stable builds for this platform.

So far, I've been able to reproduce existing cross compilation build, 
thanks to work merged in LibreOffice 7.1. We noticed the existence of 
experimental installers, built on a daily basis 
(https://ci.libreoffice.org//job/lo_daily_tb_win_arm64/).

After some discussion on 
https://ask.libreoffice.org/t/windows-arm64-listing-in-downloads-page/102870, 
it was advised to contact this mailing list.

We noticed that the lack of available machines for this platform could 
be a problem, and we discussed that with Microsoft, which could sponsors 
up to two (physical) machines for this.

Let us know how we can help!

Regards,
Pierrick