[llvm] [LLVM][Cygwin] Fix llvm-config shared library names (PR #136599)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic commented:

For the minor version thing, see #79376?  CC @tstellar @jyknight 

https://github.com/llvm/llvm-project/pull/136599