these are not complete/correct in that they do not account for ABI
variants (softfloat and coldfire fpu) in the dynamic linker name, but
I was unable to get gcc's configure to accept --with-float=soft on
m68k to test softfloat and begin figuring out how to do the spec
logic. at some point this needs to be figured out and completed, but
at least the default ABI is available in mcm now.
this patch breaks powerpc64 builds and is not necessary to produce a
working 32-bit powerpc toolchain. it seems like it may be useful for
reducing libgcc-internal bloat, but it can be reintroduced later after
it's fixed, if desired.