Enable dm-cache for kernel 3.9+

[Andy Whitcroft]

On Tue, Apr 23, 2013 at 01:50:19PM +0200, Vincent Stehlé wrote:

> While trying kernel from [1] I noticed that CONFIG_DM_CACHE was not enabled.
> 
> Could someone enable CONFIG_DM_CACHE for the future kernel builds, please?
> 
> FYI, dm-cache is a new dm target merged in kernel 3.9, which allows to
> use an SSD as a hard disk cache, for example (see [2]).
> 
> (I already asked this question to the IRC channel #ubuntu-kernel, but as
> nobody answered I repost to the ml.)

This will be switched on I believe when mainline kernels start using the
saucy configuration.  I thought this was already switched but it seems
the recent lab outage prevented that propogating.  I have just pushed
the changes to the builder and re-requested v3.9 as a test.

-apw