specs: update bit-rotted error messages.
specs: update bit-rotted error messages.

* specs/spec_helper.lua (spawn_specl, run_spec): Use the correct
function name for error messages.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

gvvaughan/specl