To clarify, the compilation problem is in the trunk.
There appears to be no problem with test_multiprocessing in the trunk 
without these lines, though.
I also think that I found the original reason for you adding those 
lines in 3.1, and that was I fixed in R70843.  Indeed, 
test_multiprocessing runs through for python_d.exe in py3k
I suggest that with the issue fixed, we remove those lines again, since 
they go against the spirit of defect http://bugs.python.org/issue4804