talloc()

[Luke Kenneth Casson Leighton]

> To track down those bugs I suggest instead we change talloc() to
> always return 0xdeadbeef for allocations of size zero. This will cause
> the bugs to show up a lot earlier and will make them easier to
> identify.

suggest putting 0xdeafbeef _before_ the malloc'd area and 0xxbeefdead
_after_.

0xdeafbeefmemmemmemmem0xbeefdead.