python: Make iterator handling Python 3 compatible

Many functions that used to return lists (e.g., dict.items()) now
return iterators and their iterator counterparts (e.g.,
dict.iteritems()) have been removed. Switch calls to the Python 2.7
iterator methods to use the Python 3 equivalent and add explicit list
conversions where necessary.

Change-Id: I0c18114955af8f4932d81fb689a0adb939dafaba
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/15992
Reviewed-by: Juha Jäykkä <juha.jaykka@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

systemc: Import tests from the Accellera systemc distribution.

Change-Id: Iad76b398949a55d768a34d027a2d8e3739953da6
Reviewed-on: https://gem5-review.googlesource.com/10845
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>