page_delete_rec_list_end(): Do not invoke page_zip_clear_rec().

page_zip_clear_rec(): Remove the global declaration.  Add an assertion
that the record must be on the free list.  Copy onl rec_offs_data_size()
bytes before attempting to clear the record and to compress the page.

page_zip_compress(), page_zip_write_rec(): Remove debug assertions that
trx_id, roll_ptr and node_ptr of deleted records be zero-filled.