I have a makefile that works transparently for Linux (x86_64) and OS X Intel (x86_64). This uses 64-bit specific GCC options.
Is there a way to adjust the makefile so that I could build for 32-bit and 64-bit OS X PPC (ppc, ppc64) without having to maintain separate, arch-specific makefiles — perhaps something like a pre-processor directive that can determine the architecture before building?