Combine multi-arch docker files

[vaibhavsood]

Hi,

Want to check if the dockerfiles in this repo can be combined into a single Dockerfile. Right now i see that ppc64le/ is a separate folder

I ran the Dockerfile under x86_64/alpine as-is on a ppc64le machine, it builds and runs correctly (should be due to the base image alpine being made multi-arch in official-images)

Doing so can help making orientdb multi-arch under official-images (this PR can be revived: docker-library/official-images#3480)

[vaibhavsood]

Hi @robfrank, want to check if i can get help with this, thanks!