Initial AIX enablement

[ecnelises]

No description provided.

[amodm]

Thanks. I don't have access to an AIX instance. If you do, can you confirm that the current unix code works for AIX?

[ecnelises]

Hi, I found this issue when building tree-sitter on AIX (one of whose subcommands depends on webbrowser to open a playground).

I'm connecting to an AIX system without graphical interface (and no usable browsers) so I can't test this crate thoroughly. AIX indeed supports X, and I went over src/unix.rs to check these are plain UNIX facilities (commands, envvar, etc.). os::tests_xdg::test_xdg_open_local_file passes.

I mark this as initial support. If someone in the future are really trying to use it in a graphical environment on AIX, I'd be glad to review.

[amodm]

That works. Some of the test failures have nothing to do with this PR, so I've merged it. I'll update here when this is out as a release.

[ecnelises]

Thanks!

[amodm]

FYI, this is now released as v0.8.13