bug#19989: 25.0.50; Build instructions on Windows

[martin rudalics]

> Assuming I'll have time to publish "everything", yes.

You will because you've just experienced how hard it is to do
"everything" without prior knowledge.

> What's in nt/INSTALL is supposed to be the important parts, though; it
> got additions as people complained about things I initially left
> unsaid.

The problem is that most users are trying to be clever.  At least I did
and AFAICT Ilya did too.  That's of no help.  What's really needed is a
stubborn, dense person who complains immediately when something doesn't
work out as written in INSTALL.

martin, sadly missing Juanma's assistance here