Add libfreexl-dev to ubuntu-precise; resolves travis-ci/apt-package-whitelist#2039
Add libfreexl-dev to ubuntu-precise; resolves travis-ci/apt-package-whitelist#2039

Packages: libfreexl-dev libfreexl1 libfreexl1-dbg

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