The issue was introduced while moving universal-binary specific trickery 
from pyconfig.h.in to a separate header file. Obviously I must have been 
drunk at the time, because I didn't move the WORDS_BIGENDIAN bits 
correctly.

The attached patch in "pymacconfig.h.patch" adds detection of 
WORDS_BIGENDIAN to pymacconfig.h, the header where the other pyconfig.h 
overrides for universal builds are as well.

Background: this work was done while adding support for 4-way universal 
builds, that is x86, x86_64, ppc and ppc64. This required many more 
updates to pyconfig.h, most of which couldn't be done in a clean 
platform-independent way. That's why I (tried to) move the setting of 
pyconfig.h values that are affected by the current architecture to 
Include/pymacconfig.h.

NOTE: I haven't tested my patch yet, I'll do a full test round later 
today.