[clang] [llvm] [libclang][Cygwin] Provide unversioned DLL file alongside versioned one (PR #147132)

[Tomohiro Kashiwada via llvm-commits]

kikairoya wrote:

> I think linking with `-lLLVM-20` should bind to `cygLLVM-20.dll`, or `cygLLVM-20.1.dll` if `-lLLVM` but is it possible?

It may be possible with llvm-dlltool but seems hacky. I've just reversed the link direction using SONAME and putting symlinks to it.

https://github.com/llvm/llvm-project/pull/147132