Cygwin-built CMake now converts paths from Cygwin to Windows form
(using cygpath -w) before they're passed to WiX.

The Wix generator on Cygwin requires the libuuid-dev package when
building CMake. However, the DLL it links to is installed by default
as part of Cygwin's core libs, so it does not need to be distributed.

If libuuid-dev isn't available, CMake is simply built without Wix
support on Cygwin.