[PowerPC] More preemptive powerpcspe ZFS build fixes

[PowerPC] More preemptive powerpcspe ZFS build fixes

I went through the merge and found the rest of the instances where
${MACHINE_ARCH} == "powerpc" was being used to detect 32-bit and adjusted
the rest of the instances to also check for powerpcspe.

mips32* will probably want to do the same.

Sponsored by:	Tag1 Consulting, Inc.