scons: use python3-compatible lists

These changes were generated using python's `2to3` tool.

Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
diff --git a/scons/custom.py b/scons/custom.py
index 955247c..09946fa 100644
--- a/scons/custom.py
+++ b/scons/custom.py
@@ -113,7 +113,7 @@
     finder = modulefinder.ModuleFinder(path=path)
     finder.run_script(node.abspath)
     results = []
-    for name, mod in finder.modules.iteritems():
+    for name, mod in finder.modules.items():
         if mod.__file__ is None:
             continue
         assert os.path.exists(mod.__file__)
@@ -189,7 +189,7 @@
     except OSError:
         return
     prefix = name + '_'
-    for flag_name, flag_value in flags.iteritems():
+    for flag_name, flag_value in flags.items():
         assert '_' not in flag_name
         env[prefix + flag_name] = flag_value
 
@@ -222,7 +222,7 @@
             raise Exception('Attempt to use unavailable module %s' % name)
 
         flags = {}
-        for flag_name, flag_value in env.Dictionary().iteritems():
+        for flag_name, flag_value in env.Dictionary().items():
             if flag_name.startswith(prefix):
                 flag_name = flag_name[len(prefix):]
                 if '_' not in flag_name:
@@ -262,7 +262,7 @@
 
         symbols = names
     else:
-        symbols = sym_table.keys()
+        symbols = list(sym_table.keys())
 
     # convert the symbol table to source lists
     src_lists = {}