Update the aarch64 build support for each OpenFaaS service

aarch64-build-support.md

Update the aarch64 build support for each OpenFaaS service

Introduction

Hi, everyone,

I have prepared a few ARM related changes and I'll be happy if someone can have a look.

• I'm updating the aarch64 build support for each OpenFaaS service:
  • More particular - faas, faas-netes, faas-swarm, nats-queue-worker
• The changes are mostly related to the makefiles and the arm64 specific dockerfiles of each project.
• The make options follow the approach set by the armhf build script Alex shared before.
  • The script itself is also updated to support both armhf and aarch64 builds.

Changes

• openfaas/faas - https://github.com/rdimitrov/faas
• openfaas/faas-netes - https://github.com/rdimitrov/faas-netes/
• openfaas/faas-swarm - https://github.com/rdimitrov/faas-swarm
• openfaas/nats-queue-worker - https://github.com/rdimitrov/nats-queue-worker
• build script - https://gist.github.com/rdimitrov/4373128eaf3b19cf83f0a29d3a5ce65b

Updates:

• It's still a draft, but also rebased the ARM64 docker-compose.yml file for faas. It's similar to the armhf one, but it uses the arm64 images we intend to build.

• Currently, the alertmanager function is failing with non-zero return (ref. alexellis2/alertmanager:v0.15.0-arm64)