[llvm] [LLVM][Examples][Cygwin] Exclude examples that are not built from test dependencies (PR #172145)

[Tomohiro Kashiwada via llvm-commits]

kikairoya wrote:

toward #171998
`Bye` and `ExampleIRTransforms` are not built on Cygwin.

https://github.com/llvm/llvm-project/blob/eeaf435859840d179e8f1df176b20449ba8ecd9e/llvm/examples/Bye/CMakeLists.txt#L9-L10

cc: @aengelke @mstorsjo @jeremyd2019 

https://github.com/llvm/llvm-project/pull/172145