perlipc.pod: correct the safe signals bypass suggestion

[stepnem]

This is a followup to the https://github.com/Perl/perl5/pull/22136#issuecomment-2262174418 discussion.

[Leont]

I'm not sure "with SigAction objects" really adds clarity here, but the "unless you set their C flag explicitly" is spot on.

[stepnem]

I'm not sure "with SigAction objects" really adds clarity here, but the "unless you set their C flag explicitly" is spot on.

Better suggestions welcome. Given that a code example immediately follows the paragraph in question, this minimal adjustment seemed adequate to me.

[khwilliamson]

I think the example is adequate to explain SigAction objects, and this PR has languished long enough