[cleanup] suppress min/max macros from windows.h the 'right way'

[neroden]

This patch suppresses the min and max macros from windows.h in the 'right way' (they're not used and are already suppressed, just not the 'clean way').  I'm hoping to switch to template versions of min and max, and this is the first step.  I can't test on Windows, so someone else please do so.  :-)

(EDIT: Note that I didn't remove the existing uses of #undef -- it's fine to suppress the unwanted macros both the "clean" way and with #undef, and probably safer to do both)

[neroden]

I notice that this has been committed, more or less (thank you  ) so this can be moved to the included-patches board

[knightly]

Moved. And thank you very much for your efforts