SPI_cursor_close — close a cursor
void SPI_cursor_close(Portal portal)
   SPI_cursor_close closes a previously created
   cursor and releases its portal storage.
  
   All open cursors are closed automatically at the end of a
   transaction.  SPI_cursor_close need only be
   invoked if it is desirable to release resources sooner.
  
Portal portalportal containing the cursor