Drop support for AIX?

[jmwilson]

None of the maintainers have access to an AIX build environment and there doesn't appear to be a turnkey low-cost way to get a hosted VM. Without knowing even the available compiler, there's no way to plan around the language standard to use, and whether the code even compiles.

[sunwire]

I am in favor of this idea.

[jonasstein]

I agree. If we have a developer with AIX someday in the future, we can still merge a PR to enable AIX support. @ninthclowd any objections to dropping AIX?