I noticed NetBSD started bogusly rreplacing EAI_NONAME with the deprecated EAI_NODATA, this was done because the haven't tagged EAI_NODATA as deprecated but also because the messsage for EAI_NONAME doesn't correspond well to EAI_NODATA.
Also, for a non.-developer end user something like "Invalid value for ai_flags" or "ai_family not supported" is not a very descriptive message.
Looking up more modern descriptions, I came up with the latest RFC 3493 with more up to date messages.
I just noticed we should also update the gai_strerror(3) man page, so that will come in a future revision.