Update llvm libs to llvm 17

[sbc100]

LLVM 17 was released a few weeks about and we already have 17.0.2:
https://discourse.llvm.org/t/llvm-17-0-2-released/73840

[sbc100]

@aheejin do you fancy having a go at this and following the instructions you wrote? If not, I'm happy to have a go.

[aheejin]

I can try that.

[sbc100]

Awesome.

Remember, the important first step is to make sure all our current changes are pushed to the branch in the llvm fork

[sbc100]

As of #21638 we are now on 18.1.2