install_prereq: Add packages for bundled pjproject

RedHat/CentOS needs python-devel
Debian/Ubuntu needs automake, libsrtp-dev and python-dev

Ubuntu also needed libncurses5-dev for cmenuselect so while not
needed for pjproject, I adedd it anyway.

Change-Id: Idf5fa16e2d87c687439621507e122cb9461d7089