branches/zip: trx_sys_create_doublewrite_buf(): Revert the change of r1208.

We cannot clear the page with memset(), because the page number and
tablespace id have already been stamped on it.

trx/trx0sys.c

@@ -275,9 +275,6 @@ trx_sys_create_doublewrite_buf(void)
 						SYNC_NO_ORDER_CHECK);
 #endif /* UNIV_SYNC_DEBUG */
 
-			/* Avoid writing uninitialized memory to disk. */
-			memset(new_block->frame, 0, UNIV_PAGE_SIZE);
-
 			/* Make a dummy change to the page to ensure it will
 			be written to disk in a flush */