src: make start of signal_wrap reenterable

[theanarkh]

make start of signal_wrap reenterable.

const Signal = internalBinding('signal_wrap').Signal;
const { signals } = internalBinding('constants').os;

const signal = new Signal();
signal.start(signals.SIGUSR2);
signal.start(signals.SIGINT);

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[aduh95]

nit

Suggested change

	if (!common.isMainThread)
	common.skip('Signal handling in Workers is not supported');
	common.skipIfWorker();