[WIP] Tracing output for chrome://tracing
This is a PoC for adding a feature to trace CMake time using chrome://tracing.
I had trouble pinpointing some performance issues in my CMakeLists, so I added this to find out where exactly the time is spent.
I don't know enough about CMake internals to make very relevant tracing, but this is enough as a CMake user to identify bottlenecks.
I used std::chrono, but I am not sure this is ok since last time I worked on CMake, C++11 was not available due to some targets of CMake not having it available.
TODO:
[ ] add an option to only trace when explicitly asked to via a CMake option [ ] add more relevant trace points ? (e.g. in Generators)