Another possible commit that deals with this issue fully. Not sure if it's the right way to do it but it works. Rather than trying to set the target_arch variable in binding.gyp it seemed just as reasonable to leave the target architecture as ppc64 as far as node-gyp is concerned. In this version find_java_libdir.sh gets the result of uname -m and uses that as the architecture value in the Java lib path.

elif [[ "${os}" == "linux" ]] && [[ "${target_arch}" == "ppc64" || "${target_arch}" == "ppc" ]]; then
    target_arch=`uname -m`
    if [[ -d ${jre_dir}/${target_arch}/classic ]]; then lib_dir="${jre_dir}"/${target_arch}/classic; else lib_dir="${jre_dir}"/${target_arch}/server; fi

This works on my ppc64le environment and it's no longer necessary to override the node-gyp environment with --target_arch=ppc64le.