configs: Use absolute import paths

Use absoluate import paths to be Python 3 compatible. This also
imports absolute_import from __future__ to ensure that Python 2.7
behaves the same way as Python 3.

Change-Id: Ica06ed95814e9cd3e768b3e1785075e36f6e56d0
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/16708
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

config: Switch from the print statement to the print function.

Change-Id: I701fa58cfcfa2767ce9ad24da314a053889878d0
Reviewed-on: https://gem5-review.googlesource.com/8762
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>

learning_gem5: Add code for hello-goodbye example

Adding more code from Learning gem5 Part II

See http://learning.gem5.org/book/part2/parameters.html

Change-Id: I9fe5655239e011c718c5cf5fd62bebcda66ea966
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/5021
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>