Raise a warning when listening for usafe signals

[quibusus]

mentioned at node interactive nodejs/code-and-learn#56

We might want to emit a warning for signals that users shouldn’t listen on (as listed in the docs warning in #8410)

[benjamingr]

You might want to elaborate on why it's unsafe in the warning text in your commit.

[addaleax]

#8601 is a PR for this.

[Trott]

@quibusus Are you still working on this?

[quibusus]

@Trott No, I'm not. There is a PR #8601, I think you can close this as duplicate

[Trott]

Closing. Feel free to re-open (or leave a comment requesting that it be re-opened) if you think it shouldn't be closed.