tests: more uniformity.

tests: more uniformity.

* tests/local.at (AT_LEX_FORMALS, AT_LEX_ARGS, AT_LEX_PRE_FORMALS)
(AT_LEX_PRE_ARGS): Rename as...
(AT_YYLEX_FORMALS, AT_YYLEX_ARGS, AT_YYLEX_PRE_FORMALS)
(AT_YYLEX_PRE_ARGS): these, for consistency.
(AT_API_PREFIX): Take %name-prefix into account.
(AT_YYLEX_PROTOTYPE): New.
Use it.
* tests/actions.at, tests/calc.at, tests/cxx-type.at: Adjust to
use them.