build python binding error on windows 10,msvc14,python3.6.

重現 Windows 10/MSVC 14/Python 3.6 的建置失敗，並檢查第 223 行附近的 boost/python/operators.hpp，以及第 40-45 行附近的 operator_l 和 operator_r 宣告。確定這段程式碼在所回報的環境中無法編譯的原因，然後確認 Python binding 在該環境中能夠成功建置，且不會引入所列出的錯誤。

D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2065: "op_": undeclared identifier
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2059: Syntax error: ">"
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2976: "boost::python::detail::operator_l": Template parameters are too few
D:\local\boost_1_67_0\boost/python/operators.hpp(40): note: See the declaration of "boost::python::detail::operator_l"
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2913: Explicit specialization; "boost::python::detail::operator_l" is not a specialization of a class template
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2065: "op_": undeclared identifier
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2059: Syntax error: ">"
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2976: "boost::python::detail::operator_r": Template parameters are too few
D:\local\boost_1_67_0\boost/python/operators.hpp(45): note: See the declaration of "boost::python::detail::operator_r"
D:\local\boost_1_67_0\boost/python/operators.hpp(223): error C2913: Explicit specialization; "boost::python::detail::operator_r" is not specialization of class template
D:\local\boost_1_67_0\boost/python/operators.hpp(224): error C2913: Explicit customization; "boost::python::detail::operator_l" is not a specialization of the class template
D:\local\boost_1_67_0\boost/python/operators.hpp(224): error C2913: Explicit customization; "boost::python::detail::operator_r" is not a specialization of the class template