tests,python: Upgrading testlib to function with Python2

Change-Id: I9926b1507e9069ae8564c31bdd377b2b916462a2
Issue-on: https://gem5.atlassian.net/browse/GEM5-395
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/29088
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
31 files changed