dynlib support for homebrew 3 on Apple Silicon M1

[OleMchls]

As the homebrew team discussed in Homebrew/brew#9177 the new library path for homebrew on apple silicon is /opt/homebrew/lib. Alongside the PR to support MacPorts #638 this commits adds support for the new homebrew path.

Fixes #880

[bbuchalter]

What's it going to take to get this merged?

[superscott]

Agreed, can we get this merged? Can confirm it fixes M1 chips that use homebrew.

[bbuchalter]

@larskanis sorry for the direct ping this is a very easy win and should be a quick review.

[larskanis]

For reference: I asked a question at homebrew about how to find homebrew installed libraries here: Homebrew/discussions#1600
They offered another possibility which is to use brew --prefix to retrieve the base path of homebrew. This would enable alternative install paths. However there is no builtin way within homebrew, that enables library loading at runtime (which is what we need by FFI).

[bbuchalter]

@tduehr thanks for the merge! Any chance we could get a point release?

[lfuelling]

@tduehr thanks for the merge! Any chance we could get a point release?

If you need it right now you can add the following line to your Gemfile:
gem 'ffi', git: 'https://github.com/ffi/ffi', ref: '82e20928319e499b2e60679205733cb5f088c363'