PowerPC code needs to be fixed

[barracuda156]

As noted in #234 arch detection for PowerPC does not work correctly, but then even that is fixed, the code itself does not work:

(gdb) run
Starting program: /opt/local/bin/cpufetch 
Reading symbols for shared libraries ++. done

Program received signal EXC_BAD_INSTRUCTION, Illegal instruction/operand.
0x00008060 in get_cpu_info ()

The functional CPU detection for PowerPC is used in OpenBLAS, maybe that could be borrowed.

Otherwise use sysctl like for aarch64 here.

[Dr-Noob]

Thanks for the feedback, but let's discuss this on the original issue (#234).