[clang] [Clang] [Driver] add a Cygwin ToolChain (PR #135691)

[via cfe-commits]

================
@@ -0,0 +1,109 @@
+//===--- Cygwin.cpp - Cygwin ToolChain Implementations ----------*- C++ -*-===//
----------------
jeremyd2019 wrote:

Like so?

https://github.com/llvm/llvm-project/pull/135691