The default version of
autoconf in 12.04 is version 2.8. How can I upgrade to autoconf 2.9?
It looks like the ppa:costamagnagianfranco PPA is no longer active or at least didn't work for me.
Instead there is a PPA available for a lot of GNU libraries at https://launchpad.net/~dns/+archive/ubuntu/gnu
For example this allowed me to install Autoconf 2.69 on Travis:
before_script: - sudo add-apt-repository ppa:dns/gnu -y - sudo apt-get update -q - sudo apt-get install --only-upgrade autoconf