Add support for FreeBSD

[kikuchan]

...and, make it easy to support additional UNIX-like systems for the future.

[evanw]

Thanks for putting this together. I understand why you refactored it this way, but I'd like to avoid metaprogramming in the makefile because I find it hard to read. I'll gladly accept the rest of the PR though. Feel free to remove the metaprogramming yourself, or I'm also happy to land it as-is and remove the metaprogramming myself afterwards if you prefer. Just let me know.

Also, can you confirm that you have tested esbuild's bundling functionality on both freebsd/amd64 and freebsd/arm64 and that it works correctly? I am unable to test this myself so this will be an unsupported build configuration, but I want to make sure someone else at least verifies that it works correctly before I start publishing builds.

[kikuchan]

Thank you for the review.
I've removed the metaprogramming in the Makefile, but still try to put them together by using platform-unixlike. How about this?

I've also tested by running make test-all on freebsd/amd64 natively and freebsd/arm64 by using qemu, and they said all passed. Of course a generated executable works fine so far.

[evanw]

That's great, thanks! And I appreciate you taking the time to test it.

[evanw]

I tried to publish it but npm's publish command failed because of their aggressive package name spam detector. I have reached out to npm support and will try to publish again once the name has been unblocked.

[kikuchan]

Oh, ok. I'm waiting for it.
Anyway, thank you for merging!

[evanw]

The esbuild-freebsd-64 package has now been published (version 0.5.24).

[kikuchan]

Thank you! I confirmed it works perfectly via npm install. I really appreciate it.