use Py_ssize_t everywhere

src/array.cc

@@ -459,7 +459,7 @@ T (*get_buffer_converter(Py_buffer *view))(const void *)
     case 'Q':
         return number_from_ptr<T, unsigned long long>;
     case 'n':
-        return number_from_ptr<T, ssize_t>;
+        return number_from_ptr<T, Py_ssize_t>;
     case 'N':
         return number_from_ptr<T, size_t>;
     case 'f':

src/array.hh

@@ -105,7 +105,7 @@ public:
         }
     }
 
-    ssize_t object_size() const;
+    Py_ssize_t object_size() const;
 
     static bool check_exact(PyObject *candidate) {
         return (Py_TYPE(candidate) == &pytype);
@@ -160,7 +160,7 @@ int coerce_to_arrays(PyObject **a, PyObject **b, Dtype *coerced_dtype);
 template <typename T> PyObject *transpose(PyObject *in, PyObject *dummy);
 
 template <typename T>
-ssize_t Array<T>::object_size() const
+Py_ssize_t Array<T>::object_size() const
 {
     int ndim;
     size_t *shape;