refactor: ensure badargs functions only reference imported symbols.
refactor: ensure badargs functions only reference imported symbols.

* lib/specl/badargs.lua (_ENV): Import all symbols used by this
module.

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

gvvaughan/specl