Jeremy noted that an option already exists in genpeimage [0] but with a different name, which I wasn't aware of: -c/control-flow-guard, instead of -g/guard-cf which I used here. I'm open to making them match.
[0] https://github.com/mingw-w64/mingw-w64/blob/70ec1e0de44f3cbed2064c08e1620ff0a7916cd1/mingw-w64-tools/genpeimg/src/genpeimg.c#L84
