Linux: make it possible to build with third_party/xdg-utils directory removed
Linux: make it possible to build with third_party/xdg-utils directory removed

This is useful for Linux distributions that remove third party directories
to ensure that the bundled versions will not be used.

In fact, this is upstreaming a Gentoo Linux patch.

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/6282005

git-svn-id: http://src.chromium.org/svn/trunk/src@71672 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 453044f8fe598581567fc1cf29d9a0991d486a0e
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