Do you not have that file ? I find it in my Platform SDK's Lib folder. It should be readily available but just /msg me if you want me to send a copy of it over.
I've got the 64-bit MinGW compiler, and it seems to be basically functional, but I haven't got round to thinking about the changes one would have to make to the perl source (makefile.mk mainly, I guess) in order to build perl with that compiler. If you get somewhere with that I would be interested to hear about it.