Function swap

test/arrayfire_test.cpp:1458–1462

template<typename T>
void swap(sparseCooValue<T> &lhs, sparseCooValue<T> &rhs) {
    std::swap(lhs.row, rhs.row);
    std::swap(lhs.col, rhs.col);
    std::swap(lhs.value, rhs.value);
}

template<typename T>
bool operator<(const sparseCooValue<T> &lhs, const sparseCooValue<T> &rhs) {