Is there a reason why CPP is set to
${CC} -E ${CPP_PRECOMP_FLAGS} on Darwin instead of
cpp ${CPP_PRECOMP_FLAGS}?

I just had to realize, at least on Tiger, that gcc -E -traditional-cpp
is not equivalent to cpp -traditional-cpp.

-- 
Georg Schwarz    http://home.pages.de/~schwarz/
 georg.schwarz@freenet.de  +49 178 8545053