xz compression and mysql-5.5

[Nicholas Bamber <nicholas@periapt.co.uk>]

Ansgar,
	I have not finished testing your patch but I have a few questions.

	Firstly it raises a new lintian error requiring a Pre-Depends on dpkg
(=> 1.15.6~). I know that this is more of an issue for Ubuntu and that
Ubuntu won't in this case be syncing from wheezy, so I guess we can live
with the warning. But to be careful I thought I had better run it past
you. I certainly would want to follow lintian's advice post-wheezy.

	Also you say " please keep in mind to not include additional changes."
however I also have #683733  to fix which I think I should be in the
same release.