stop using dict iter* helpers

Change from iter{keys,items,values}() to {keys,items,values}().
Python 3 doesn't offer the iter variants, and we don't really have
any cases where performance is critical where we'd need to avoid
creating the temporary list (which is what Python 2 does).

This is mostly mechanical.

BUG=chromium:980619
TEST=lint is unchanged in chromite
TEST=unittests pass

Change-Id: I591110f2eb5d43bb9268b975b14bd7ade66a4e35
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1689014
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: David Burger <dburger@chromium.org>
diff --git a/scripts/cros_sdk.py b/scripts/cros_sdk.py
index cf7db96..23ebe53 100644
--- a/scripts/cros_sdk.py
+++ b/scripts/cros_sdk.py
@@ -526,7 +526,7 @@
     for mod, so in apache_modules:
       for f in glob.glob(os.path.join(g, so)):
         module_dirs.setdefault(os.path.dirname(f), []).append(so)
-  for apache_module_path, modules_found in module_dirs.iteritems():
+  for apache_module_path, modules_found in module_dirs.items():
     if len(modules_found) == len(apache_modules):
       break
   else: