How to get values for rtlbootstrap.mk in configure?

[Matúš Kukan]

Hello,

I just remembered that rtlbootstrap.mk is empty for Windows for quite
some time now.
http://cgit.freedesktop.org/libreoffice/core/tree/sal/CustomTarget_generated.mk#n36

That's probably not good.
There is a comment that the variables (RTL_OS RTL_ARCH) should be set
by configure
http://cgit.freedesktop.org/libreoffice/core/tree/sdext/platform.mk#n28

How could I do that ?
Well, it's easy to get the values for my platform but how to do it for all ?
Somebody wants to do it as an easy hack ;-) ?

Thanks,
Matus