misc: Views and Iterators instead of Lists in python3

misc: Views and Iterators instead of Lists in python3

* dict methods dict.keys(), dict.items() and dict.values()
return "views" instead of lists

* The dict.iterkeys(), dict.iteritems() and dict.itervalues()
methods are no longer supported.

* map() and filter() return iterators.

* range() now behaves like xrange() used to behave, except it works with
values of arbitrary size. The latter no longer exists.

* zip() now returns an iterator.

Change-Id: Id480018239db88d7f5d60588c93719056de4a0c0
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/26248
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>