tests: enlarge the allowed duration for calc tests

Hydra "often" fails on this test:

252. calc.at:658: 252. Calculator %glr-parser api.pure
parse.error=verbose %debug %locations %defines api.prefix="calc"
%verbose %yacc %parse-param {semantic_value *result}
%parse-param {int *count} (calc.at:658): FAILED

* tests/calc.at: Give 200s instead of 100s.
Use AT_DEBUG_IF.