dib-init-system script is installed into $PATH. Called
without arguments it will print the name of init system
used to stdout.
Additionally, set DIB_INIT_SYSTEM environment variable to
the init system used.
Tested on ubuntu+upstart, centos+upstart, fedora+systemd,
debian+sysv.
Closes-Bug: #1251610
Change-Id: I29668079091f6060dab66d8259890384d3bbd653
Many python extensions are built from source each time an image is
built. Repeating these is wasteful, so ccache is employed to eliminate
that waste. A cache dir outside the chroot is used to speed up
subsequent image builds.
Change-Id: Ib73563ddbe5f3be7454bfc54ab91cedb559a1304