[llvm] Overhaul the TargetMachine and LLVMTargetMachine Classes (PR #111234)

[Justin Bogner via llvm-commits]

bogner wrote:

> What's broken is the experimental targets, which in theory you shouldn't have to worry about. You still get the build failure notifications, so this is a dumb system. We should either not notify on experimental target builds, or get rid of the concept entirely

I posted https://discourse.llvm.org/t/rfc-llvm-experimental-targets-to-build-helps-no-one/83148 saying we should really just get rid of the experimental targets concept.

https://github.com/llvm/llvm-project/pull/111234