cygwin specific c files for parrot

[Hill Stephen-STEHILL1]

Hi,
I have a custom matherr() function (matherr.c) I'm experimenting with to solve 
#36865 ( Test 17 of t/op/trans.t failing on Cygwin ). If I put it in 
platform/win32 it doesn't get picked up. Where should it go in order to to be 
picked up as cygwin-specific. (It may be that it is needed for win32 as well, 
but my platform is cygwin).
 
Best regards
 
Steve