Add libgdl-3-dev to ubuntu-precise; resolves travis-ci/apt-package-whitelist#2700
Add libgdl-3-dev to ubuntu-precise; resolves travis-ci/apt-package-whitelist#2700

Packages: libgdl-3-dev libgdl-3-5 libgdl-3-common libgdl-3-doc libgdl-3-dbg gir1.2-gdl-3

travis-ci/apt-package-whitelist,travis-ci/apt-package-whitelist