operator>> for complex<T> uses std::ostream, not std::istream

[brian-kelley]

In Kokkos_Complex.hpp, there are operator overloads to allow input and output of complex through std streams. But the input operator>>() takes a std::ostream&, not a std::istream&. When I tried to read a complex from a std::istringstream, I got a "no matching function to call" error, since istringstream is not a subclass of ostream.

Line 790 or so (bottom of file) in Kokkos_Complex.hpp (in develop, but the issue is also present in master):

template<class RealType>
std::ostream& operator << (std::ostream& os, const complex<RealType>& x) {
  const std::complex<RealType> x_std (Kokkos::real (x), Kokkos::imag (x));
  os << x_std;
  return os;
}

template<class RealType>
std::ostream& operator >> (std::ostream& os, complex<RealType>& x) {
  std::complex<RealType> x_std;
  os >> x_std;
  x = x_std; // only assigns on success of above
  return os;
}