[Interest] Provide a Means to Make Static Builds of Qt 6.1 for Android, macOS, Windows and GNU/Linux

[Marius Kittler]

> However, configuring and building Qt on Microsoft Windows on a Windows
> host with either MinGW or MSVC has been impossible.

I did it in the past and it is doable. However, I must also say that Windows 
is not my preferred platform for development. So for years I'm now conducting 
my Windows builds also on GNU/Linux, specifically Arch Linux where I maintain 
packages for cross compilation including static variants:

https://aur.archlinux.org/packages/?K=mingw-w64-qt5
https://aur.archlinux.org/packages/?K=mingw-w64-qt6

I spend some effort so static linking works also for Qt's dependencies so that 
the final executable only depends on libraries provided by Windows itself. 
However, I must also say that this kind of cross compilation is not supported 
by upstream.

> I would like to have virtual machines or Docker containers that allow
> me to build Qt statically for all prior mentioned platforms. If it's
> possible to use coin's scripts locally instead, please tell me how.

I personally just use an Arch Linux machine directly but it would of course be 
possible to use Docker (like https://github.com/mdimura/docker-mingw-arch).
Of course you can also just use the Arch PKGBUILDs as a template to create 
your own build scripts and just run them under any distribution.

There's of course also https://github.com/mxe/mxe which also allows to make a 
static Qt build. I suppose they lack Qt 6 builds, though. I'm also not sure 
whether there's a binary repository (at least provided by some community 
member).

For native compilation under Windows MSYS2 is also an option. Not sure how 
well their static variants work, though.