Revert "cpan/Time-HiRes/t/itimer.t: better diagnostics"

This reverts commit 65dd9533e90d8e1ea84c091ff43133132c667a1c.

That commit was just temporary to help debug a smoke issue.
Since Time::Hires is a CPAN-first module, back the patch out from blead,
and leave it to the module's owner whether they want to add it back in.