arm64 support

[pieroproietti]

I want to know if it is possible, add arm64 packaging in oclif-dev.

I wrote penguins-eggs a Linux remaster/installer system using this framework, and I'm able to produce debian packages for armel, i386 and amd64.

I want to know if there is same possible way to add arm64 architecture.

Thanx

[pieroproietti]

I was able to compile against arm64, just two simple adds in my dev-cli fork and it works!

I think can usefull for some others too.