Add chrome/installer/mac/third_party/xz/xz to .gitignore.
Add chrome/installer/mac/third_party/xz/xz to .gitignore.

BUG=None
TEST=Less Git clutter.
TBR=mark@chromium.org

Review URL: http://codereview.chromium.org/2862030

git-svn-id: http://src.chromium.org/svn/trunk/src@50972 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 26e58b7636b96676791a61f264fdd3a46e765907
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser