CHGAME_DEBUG and CHGAME_PROFILE: set them with build.extra_flags.

Switch	Default	What it turns on
`CHGAME_DEBUG`	0 on the board, 1 in the simulator	the serial debug protocol (Debug protocol): screenshots, input injection, lockstep, perf. Always on in the simulator, which is driven through it; off on the board unless asked for (it costs ~2 KB and needs USB Serial).
`CHGAME_PROFILE`	0	the section profiler (dbg::prof() and the `T` command)

arduino-cli compile --build-property build.extra_flags=-DCHGAME_DEBUG=1 ...

(chgame build --debug does this.) A sketch can test them too, as #if CHGAME_DEBUG, to leave things out of its debug build.