Raise a warning when listening for usafe signals
Checklist
- [x ]
make -j4 test
(UNIX) - [x ] tests and/or benchmarks are included
- [nodejs/node#8410] documentation is changed or added
- [ x] commit message follows commit guidelines
Description of change
We might want to emit a warning for signals that users shouldn’t listen on (as listed in the docs warning in nodejs/node#8410)