Method on_int64

test/basic_parser.cpp:1696–1696

            bool on_string( SV, std::size_t, std::error_code& ) { return true; }
            bool on_number_part( SV, std::error_code&) { return true; }
            bool on_int64( std::int64_t, SV, std::error_code& ) { return true; }
            bool on_uint64( std::uint64_t, SV, std::error_code& ) { return true; }
            bool on_double( double, SV, std::error_code& ) { return true; }
            bool on_bool( bool, std::error_code& ) { return true; }