Add powerpc64 support

[sebimarkgraf]

Tries to add the same support for powerpc64.

Implementation based on https://github.com/torvalds/linux/blob/master/arch/powerpc/kernel/syscalls/syscall.tbl and https://www.kernel.org/doc/html/next/arch/powerpc/syscall64-abi.html

Still need to check on a powerpc64 system.