Bug#789094: enable CONFIG_ZBUD again like in 3.16

[Kai Lüke <kailueke@riseup.net>]

Package: linux-image-4.0.0-1-amd64
Version: 4.0.2-1

Hello,

when switching from 3.16 to 4.0 with kernel command line zswap.enabled=1
the following messages are printed and zswap is not working.

[    0.898384] zpool: loaded
[    0.930753] zswap: loading zswap
[    0.930755] zpool: creating pool type zbud
[    0.932435] zpool: no driver for type zbud
[    0.932508] zswap: zbud zpool not available
[    0.932567] zswap: zpool creation failed

zbud is the default memory allocation backend used in zswap. In 3.16
CONFIG_ZBUD was enabled but in 4.0 it is not. I could not find a note on
this in the changelog and am so asking whether it can be enabled again.

Thanks,
Kai