Bitten by macros, again.
See 680b715518.
* data/variant.hh (_b4_symbol_constructor_declare)
(_b4_symbol_constructor_define): Do not use user types, which can
include commas as in `std::pair<int, int>`, to macros.
* tests/local.at: Adjust the lex related macros to support the
case of token constructors.
* tests/types.at: Also check token constructors on types with commas.