More work on IRQ/ISR
seems one of the simulation headers include a "wrapper.h", which overrides
the native qnx functions. The replaced function `MyInterruptDetach()` does
never return. After calling `MyInterruptAttach()` (which is the override for
`InterruptAttach()`) there is very high CPU load. I hope the native functions
work with our implementation, we have to test this on the real hardware.