Packaging: Add the missing dependencies

automake and pkg-confg are needed when building ovirt-guest-agent in a
fresh Ubuntu environment.

This patch also split each dependency to separated lines. The debhelper
is a boilerplate so leave it at the first line. The other lines are
custom dependencies so sort them to make it easier to maintain.

Change-Id: I90f86100946c5b60cc816e664a2857cad5b4b0f5
Signed-off-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>