Disable specialization of StaticThread if signals are disabled
Disable specialization of StaticThread if signals are disabled

When signals are disabled, specialization of StaticThread which supports
signals is also disabled.
DISTORTEC/distortos,jasmin-j/distortos,CezaryGapinski/distortos,CezaryGapinski/distortos,jasmin-j/distortos,DISTORTEC/distortos,CezaryGapinski/distortos,DISTORTEC/distortos,jasmin-j/distortos,CezaryGapinski/distortos,DISTORTEC/distortos,jasmin-j/distortos,CezaryGapinski/distortos,jasmin-j/distortos