[Perl/perl5] a769d3: eval_sv(): improve code comment

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: a769d3e640ceecd7ce719115d3f36d2194247282
      https://github.com/Perl/perl5/commit/a769d3e640ceecd7ce719115d3f36d2194247282
  Author: David Mitchell <davem@iabyn.com>
  Date:   2023-03-01 (Wed, 01 Mar 2023)

  Changed paths:
    M perl.c

  Log Message:
  -----------
  eval_sv(): improve code comment

Explain in detail why the return arg on the stack from the eval can't be
NULL on successful compilation.

(Spotted by Hugo)

• [Perl/perl5] a769d3: eval_sv(): improve code comment by iabyn via perl5-changes