Update PyBuffer_Release() declaration to match new buffer API.

See
  http://docs.python.org/c-api/buffer.html#PyBuffer_Release
for the authoritative definition.

Cython/Includes/cpython/buffer.pxd

@@ -49,9 +49,9 @@ cdef extern from "Python.h":
 
     # 0 is returned on success and -1 on error.
 
-    void PyBuffer_Release(object obj, object view)
-    # Release the buffer view over obj. This should be called when the
-    # buffer is no longer being used as it may free memory from it.
+    void PyBuffer_Release(Py_buffer *view)
+    # Release the buffer view. This should be called when the buffer
+    # is no longer being used as it may free memory from it.
 
     void* PyBuffer_GetPointer(Py_buffer *view, Py_ssize_t *indices)
     # ??