specl: remove loadstring fallback for failed yaml load.
specl: remove loadstring fallback for failed yaml load.

* src/specl.in (slurp): Go straight to setting an error messaage
if the yaml.load fails.

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

gvvaughan/specl