Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party

Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party.

README.chromium will be placed in the Chromium tree in the directory that
receives xz. Here are its contents, which provide information about xz:

--
Name: XZ Utils
URL: http://tukaani.org/xz/
Source URL: git://ctrl.tukaani.org/xz.git
Version: git commit c15c42abb3c8c6e77c778ef06c97a4a10b8b5d00
         (2010-06-15 14:06:29 +0300), newer than 4.999.9beta
License: Public domain/license grant, LGPL 2.1, GPL 2, GPL 3
License File: COPYING

Description:
XZ Utils is general-purpose data compression software implementing the
modified Lempel-Ziv-Markov chain algorithm (LZMA2).

Local Modifications:
 - None.
--

BUG=47199
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=50504

[TVL, 2010-06-22 19:33:20]

<rubber_stamp>lgtm</rubber_stamp>

will a .gyp file also go in that parent directory (along with the svn:ignore)?

do you want to open a bug about getting the windows build to use this all src
version inplace of the other partial copy that's checked in?

[Mark Mentovai, 2010-06-22 19:36:06]

TVL wrote:
> <rubber_stamp>lgtm</rubber_stamp>
>
> will a .gyp file also go in that parent directory (along with the
> svn:ignore)?

That’s gonna come next, once this is czeched in.

> do you want to open a bug about getting the windows build to use this all
> src version inplace of the other partial copy that's checked in?

Frankly, I’d rather bury my head in the sand.