maint: access _ENV with rawget to satisfy std.strict.
maint: access _ENV with rawget to satisfy std.strict.

* lib/specl/runner.lua (initenv): Access _ENV with rawget.

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

gvvaughan/specl