Feature Request: Support for slow flashcarts/hardware.

[RetroGamer02]

There are cases where the current value of REG_WAITCNT does not allow the game to run.
For these cases could you add support for REG_WAITCNT = B645;
If not don't worry about it it would just be nice.

See https://github.com/XProger/OpenLara/blob/master/src/platform/gba/checkROM.cpp for a reference of how it could be done.