Relicense from MIT -> Apache 2.0 with LLVM exceptions

[ednolan]

As of December 14, 2025, the Beman Project decided to remove the MIT license as a supported license. This is due to implementer concerns that the MIT license's attribution clause makes MIT-licensed code unshippable in standard library implementations:

https://old.reddit.com/r/cpp/comments/1pb6573/standard_library_implementer_explains_why_they/

For more details, see this pull request:

bemanproject/beman#189

[ednolan]

@TedLyngmo Please take a look at this pull request. I won't be able to merge it without your approval.

[coveralls]

coverage: 100.0%. remained the same
when pulling 40aa816 on enolan_relicense1
into ce2ef64 on main.

[TedLyngmo]

@ednolan Hmm, odd. Isn't the Apache license saying essientially the same thing, requiring the standard library distribution to include the license too: "You must give any other recipients of the Work or Derivative Works a copy of this License; and"... ?

I see the exceptions to compiled software, but most of any standard library implementation will not be compiled so I don't see how that license helps. I use the MIT license on another library that I've written that I know has gone through at least one major international company's legal dept. without this concern being raised.

I think it's a mistake, but I'll approve the change for now. Hopefully someone can shed some light on this in the future. The reddit thread wasn't really 100% clear i.m.o.