Add cdbs to install-build-deps

The Common Debian Build System (cdbs) is needed for
packaging .deb files in some configurations.

http://packages.ubuntu.com/search?keywords=cdbs
shows that it's available for all common Ubuntu
distributions.
On Precise and Trusty, the package is very small (~40kB),
so it shouldn't have much impact on users.

TESTED=ran install-build-deps.sh on Ubuntu Precise.
R=friedman@chromium.org

Review URL: https://codereview.chromium.org/531513002

Cr-Commit-Position: refs/heads/master@{#295674}

build/install-build-deps.sh

@@ -94,8 +94,8 @@ fi
 chromeos_dev_list="libbluetooth-dev libxkbcommon-dev"
 
 # Packages needed for development
-dev_list="apache2.2-bin bison curl dpkg-dev elfutils devscripts fakeroot flex
-          fonts-thai-tlwg g++ git-core git-svn gperf language-pack-da
+dev_list="apache2.2-bin bison cdbs curl dpkg-dev elfutils devscripts fakeroot
+          flex fonts-thai-tlwg g++ git-core git-svn gperf language-pack-da
           language-pack-fr language-pack-he language-pack-zh-hant
           libapache2-mod-php5 libasound2-dev libbrlapi-dev libav-tools
           libbz2-dev libcairo2-dev libcap-dev libcups2-dev libcurl4-gnutls-dev