Add a script to build inside Docker
Add a script to build inside Docker

This allows phosphor-event to be on a machine with Docker installed
that does not have all the dependencies installed.

A docker container is built and used for the build process, with the
binary built in-place.

Signed-off-by: Joel Stanley <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@jms.id.au>

openbmc/phosphor-event,openbmc/phosphor-event,openbmc/phosphor-event