Add "#include <functional>" in StaticThread.hpp
Add "#include <functional>" in StaticThread.hpp

Without this, compilation with toolchain based on GCC 7 fails with
"error: 'bind' is not a member of 'std'".
CezaryGapinski/distortos,DISTORTEC/distortos,jasmin-j/distortos,CezaryGapinski/distortos,jasmin-j/distortos,CezaryGapinski/distortos,jasmin-j/distortos,DISTORTEC/distortos,CezaryGapinski/distortos,jasmin-j/distortos,CezaryGapinski/distortos,DISTORTEC/distortos,DISTORTEC/distortos,jasmin-j/distortos