Add libextlib-ocaml-dev to ubuntu-precise; resolves travis-ci/apt-package-whitelist#3910
Add libextlib-ocaml-dev to ubuntu-precise; resolves travis-ci/apt-package-whitelist#3910

Packages: libextlib-ocaml-dev libextlib-ocaml

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