configs: Fix import path error in learning_gem5 part3

Change-Id: I2c5cd22bded998bae8e7aa77e42e1b042ce1c5f5
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17869
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>

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>

learning_gem5: Ruby random tester files for MSI

Adds a pair of scripts to run the Ruby random tester with the MSI protocol.

This code follows Learning gem5 Part 3.
http://learning.gem5.org/book/part3/index.html

Change-Id: I15550a36618546f0354163b0216cf771f434ed84
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/8944
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>