Add homebrew include path for arm based homebrew

[dajabe]

Update for PR #85
Cleaned up commit history added path to CXXFLAGS as I needed that on my setup.

[odarriba]

@westonplatter sorry to mention you, but this PR has been around for ~6 months, can we make it merged and release a new version?

M1 and M2 based Macbooks are quite popular nowadays and this is stopping macOS based develoeprs to install this gem :(

If we can help in anything to make this happen please let us know - we know and understand that open source software may not be a priority. Thanks for your awesome work.

Edit: in case anyone is facing this issue: https://stackoverflow.com/questions/66494253/error-when-installing-gem-phashion-ld-library-not-found-for-ljpeg

[SixiS]

@westonplatter sorry for the re-ping.
This PR fixes it for me as well.

[pgib]

One option people can do is just fork the repo and use Github's Rubygem System.

[ndbroadbent]

I just pushed a new commit to this PR which also updates config.guess and config.sub (same as #100.) I needed to update these files when building ARM Docker images

[khasinski]

We actually ported the code to native ruby (well, VIPS-backed, but RMagick should also be doable and should be released soon) because of this and another build breaking issue, here is the link: https://github.com/khasinski/phash-rb