[AD] universal binary of 4.2?

[Jon Rafkind <workmin@xxxxxxxxxx>]

How do I go about making a universal dylib( osx ) of 4.2? I see in
makefile.osx stuff about ifdef UB; CFLAGS += -arch ppc -arch i386; but
when I define UB I get the following error

gcc -DALLEGRO_SRC -DALLEGRO_LIB_BUILD  -Wall -Wno-unused
-Wno-long-double  -O2 -funroll-loops -ffast-math -fomit-frame-pointer
-fno-common -pipe -dynamic -arch ppc -arch i386 -DALLEGRO_NO_ASM
-Ilibpng -I. -I./include -o obj/macosx/alleg/allegro.o -c src/allegro.c
gcc: installation problem, cannot exec 'i686-apple-darwin8-gcc-4.0.0':
No such file or directory
lipo: can't figure out the architecture type of: /var/tmp//ccbpYPmx.out
make: *** [obj/macosx/alleg/allegro.o] Error 255