Move cmake compile options to the example project (#872)

Move cmake compile options to the example project (#872)

* Move GCC compile option to GCC folder with toolchain option

* Add CI flow to build cmake example

* Fix CI

* formatting && enable Werror

* Add useless variable to test CI

* revert useless variable

* Add comments as examples.

* Remove default compile options.

* Formatting

* Remove compile option in kernel cmake and put the sample in examples/cmake_example

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Co-authored-by: Joseph Julicher <jjulicher@mac.com>