[Cygwin] Fix global variable dll import (#121439)
This PR is necessary for cygwin target of Rust.
References:
*
https://github.com/rust-lang/llvm-project/commit/86657cc39f8e42ae73be810fb0703ddac0eeef94
*
https://github.com/Berrysoft/llvm-project/commit/a807e9f077351d3c6a68f4abe74c94a039759a2e
