[Perl/perl5] a3e693: don't read DATA when it is closed

[Tony Cook via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: a3e693309fe5a17301c8ed638cbf3cdfee7253bc
      
https://github.com/Perl/perl5/commit/a3e693309fe5a17301c8ed638cbf3cdfee7253bc
  Author: Tony Cook <t...@develop-help.com>
  Date:   2020-11-03 (Tue, 03 Nov 2020)

  Changed paths:
    M t/loc_tools.pl

  Log Message:
  -----------
  don't read DATA when it is closed

This has been producing noise for a while, but some recent change
meant it started some warning tests failing.