build-setup.sh: new option to only build the container

Starting to see incompatibilities in the latest Ubuntu releases with
older levels of code so it will be useful to have a way to utilize this
script to build older Ubuntu release docker containers and then utilize
them on newer Ubuntu machines.

Tested:
- Verified the new env variable worked as expected
- Verified when the env variable is not set, code behaved as it used to

Change-Id: I95eb0ea1a1c52e0ef50390fa1978590024170bf5
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
1 file changed