StaticSignalsReceiver: inherit from SignalsReceiver
StaticSignalsReceiver: inherit from SignalsReceiver

This effectively reverts 42b2a0c2a25fd851294d83d25ae0c3c7b569b258 - now
correct order of construction and destruction is guaranteed by proper
use of unique_ptr.
DISTORTEC/distortos,CezaryGapinski/distortos,CezaryGapinski/distortos,CezaryGapinski/distortos,DISTORTEC/distortos,DISTORTEC/distortos,jasmin-j/distortos,DISTORTEC/distortos,CezaryGapinski/distortos,jasmin-j/distortos,jasmin-j/distortos,CezaryGapinski/distortos,jasmin-j/distortos,jasmin-j/distortos