[libcxx] [libcxxabi] [libunwind] [llvm] [runtimes] remove workaround for old CMake when setting `--unwindlib=none` (PR #93429)

[via cfe-commits]

h-vetinari wrote:

> So that cmake issue seems to be really, really unfortunate here. :-( I wonder if the cure is worse than the disease here [...]

Yup, that's a distinct possibility IMO...

> [...] and if it would be better to just keep what we have now - and simplify it only if cmake adds something like `CMAKE_REQUIRED_DYNAMIC_LINK_OPTIONS` or so.

It would probably make sense to report back on the CMake issue how big the fallout from this is? Perhaps the CMake devs would reconsider, or at least take it as an indicator for the necessity of `CMAKE_REQUIRED_DYNAMIC_LINK_OPTIONS`? I think you understand the problem space much better than me (I'm mostly stumbling around in a dark room TBH), so if you could do that that would be great!

https://github.com/llvm/llvm-project/pull/93429