Merging feature/windows-cross-build

[Jan-Marek Glogowski]

Hi everyone,

on and off I've been working on building LibreOffice for Windows Arm64.
Since I'm lacking any Arm64 hardware and running the build would
probably take ages anyway, I decided to do a cross build and just test
the result and fix the fallout on QEMU with Windows Arm64. (Ok - I know,
I could eventually run Windows Arm64 on my phone, which some people do
via a Linux chroot running a Aarch64 KVM QEMU to play Windows games, but
I digress…)

While the Arm64 part in private/jmux/win-arm64 locally currently builds,
using a definitely broken bridge, I still have problems with QEMU
running the current Windows Arm64 installer without massive timeouts. I
also sent some upstream patches to libvirt, so it can do a Windows 10
Arm64 install from ISO.

So this is just about the feature/windows-cross-build patches, which fix
the cross-build target for me (AKA "works for me" TM).

These generally contain some large configure changes, like the drop of
the --enable-64bit configure option. Instead the build now uses standard
--host and --build options. So on Cgywin64, the default build will now
result in a 64bit LO.

This will require changes to all non distro-configs based Windows
tinderboxes and adaption of the build instructions, notwithstanding the
general fallout, likely from the change Java NI build handling of the
office bean. I've also build Android at some point.

Results from CI are currently green in
https://gerrit.libreoffice.org/c/core/+/99717

What the best time and way to merge these patches?
Anyone else want to test or review?

Jan-Marek

P.S. I tested my builds with

--with-package-format=msi
--with-ucrt-dir=c:/lode/ucrt-redist

## pseudo-cross build
## cygpath -ms '/cygdrive/c/Program Files
(x86)/AdoptOpenJDK/jdk-14.0.2.12-hotspot'
--build=i686-pc-cygwin
--host=x86_64-pc-cygwin
--with-build-platform-configure-options=--with-jdk-home=C:/PROGRA~2/ADOPTO~1/JDK-14~1.12-
--with-jdk-home=/cygdrive/c/Program Files/Java/jdk-14.0.1

## x64 => x86 - no cross build
--host=i686-pc-cygwin
--with-jdk-home=/cygdrive/c/Program Files
(x86)/AdoptOpenJDK/jdk-14.0.2.12-hotspot

# x64 => arm64 - cross build
--host=aarch64-pc-cygwin
--with-build-platform-configure-options=--with-jdk-home=C:/PROGRA~1/Java/JDK-14~1.1
--with-jdk-home=/cygdrive/c/lode/jdk-16-ea+25-windows-aarch64

and also just a plain x86_64 build.