Monitoring components for CPU/segmentation faults

[Duss Pirmin]

Hello Genodians

While searching for a solution to the problem of misbehaving components 
I stumbled upon
`test-fault_detection` which gave me the idea to let init monitor the 
PD/CPU session of
its children and report the error.

The idea is that a monitor component can then decide what to do about 
the failure.

I have drafted what I envision in [1]. It is not yet complete, as I'm 
not sure on how to
safely remove the signal handlers if in a config change the monitoring 
is disabled.

If you think this feature would be useful, I'd create an issue where the 
implementation details
could be discussed.

On the other hand maybe someone has an other idea how a similar 
functionality can be achieved.

[1] https://github.com/trimpim/genode/tree/sandbox-fault_detection