[C++-sig] np.int64 does not match unsigned long on py3?

[Neal Becker]

Using boost::python,
it seems a python arg of type np.int64 will match a call requiring
c++ type size_t on python2, but on python3 I get:

   burst.pilot_xsyms = gold_code_generator (-1, -1) (burst.n_pilot_syms)
Boost.Python.ArgumentError: Python argument types in
    gold_code_generator.__call__(gold_code_generator, numpy.int64)
did not match C++ signature:
    __call__(gold_code_generator {lvalue}, unsigned long)
    __call__(gold_code_generator {lvalue})

Any ideas?