Fix building on M1 macOS

[LinusU]

• Have you updated CHANGELOG.md? (same line as Update has_lib.js to support Apple M1 with homebrew #1872)

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This change JPEG detection to go thru pkg-config.

I also needed to add the new homebrew directory to the gif part in order for it to pick up giflib. I did try to also add /no/folder/here to see that it doesn't error out if the folder doesn't exists, and that seems to work.

That being said, it would be great if some people can try this out on different operating systems!

fixes #1839 #1733

[tansanDOTeth]

I installed this package with the command below. I am still getting this error Symbol not found: _cairo_fill.

npm install Automattic/node-canvas#m1

[donmccurdy]

This PR fixes the issue I'd reported in #1923, thanks!

• macOS Monterey 12.0.1
• M1 Pro chip

[zbjornson]

Let's go with it then!

I'll try to make builds and a release this weekend btw (although we don't have ARM builds setup).