misc: Use python 3's argumentless super().

When calling a method in a superclass, you can/should use the super()
method to get a reference to that class. The python 2 version of that
method takes two parameters, the current class name, and the "self"
instance. The python 3 version takes no arguments. This is better for a
at least three reasons.

First, this version is less verbose because you don't have to specify
any arguments.

Second, you don't have to remember which argument goes where (I always
have to look it up), and you can't accidentally use the wrong class
name, or forget to update it if you copy code from a different class.

Third, this version will work correctly if you use a class decorator.
I don't know exactly how the mechanics of this work, but it is referred
to in a comment on this stackoverflow question:

https://stackoverflow.com/questions/681953/how-to-decorate-a-class

Change-Id: I427737c8f767e80da86cd245642e3b057121bc3b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52224
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/SConscript

@@ -94,7 +94,7 @@ class PySource(SourceFile):
 
     def __init__(self, package, source, tags=None, add_tags=None):
         '''specify the python package, the source file, and any tags'''
-        super(PySource, self).__init__(source, tags, add_tags)
+        super().__init__(source, tags, add_tags)
 
         basename = os.path.basename(self.filename)
         modname, ext = os.path.splitext(basename)
@@ -145,7 +145,7 @@ class SimObject(PySource):
     def __init__(self, source, tags=None, add_tags=None):
         '''Specify the source file and any tags (automatically in
         the m5.objects package)'''
-        super(SimObject, self).__init__('m5.objects', source, tags, add_tags)
+        super().__init__('m5.objects', source, tags, add_tags)
         if self.fixed:
             raise AttributeError("Too late to call SimObject now.")
 
@@ -226,7 +226,7 @@ class TopLevelMeta(type):
 
     def __init__(cls, name, bases, d):
         TopLevelMeta.all.append(cls)
-        super(TopLevelMeta, cls).__init__(name, bases, d)
+        super().__init__(name, bases, d)
         cls.all = []
 
 class TopLevelBase(object, metaclass=TopLevelMeta):
@@ -235,7 +235,7 @@ class TopLevelBase(object, metaclass=TopLevelMeta):
     def __init__(self, target, *srcs_and_filts):
         '''Specify the target name and any sources. Sources that are
         not SourceFiles are evalued with Source().'''
-        super(TopLevelBase, self).__init__()
+        super().__init__()
         self.all.append(self)
         self.target = target
 
@@ -325,7 +325,7 @@ class Gem5(Executable):
         env.Depends(date_obj, objs)
         objs.append(date_obj)
 
-        return super(Gem5, self).declare(env, objs)
+        return super().declare(env, objs)
 
 
 class GTest(Executable):
@@ -334,7 +334,7 @@ class GTest(Executable):
     def __init__(self, *srcs_and_filts, **kwargs):
         if not kwargs.pop('skip_lib', False):
             srcs_and_filts = srcs_and_filts + (with_tag('gtest lib'),)
-        super(GTest, self).__init__(*srcs_and_filts)
+        super().__init__(*srcs_and_filts)
 
     @classmethod
     def declare_all(cls, env):
@@ -345,10 +345,10 @@ class GTest(Executable):
         env.Append(CPPFLAGS=env['GTEST_CPPFLAGS'])
         env['GTEST_OUT_DIR'] = \
             Dir(env['BUILDDIR']).Dir('unittests.${ENV_LABEL}')
-        return super(GTest, cls).declare_all(env)
+        return super().declare_all(env)
 
     def declare(self, env):
-        binary, stripped = super(GTest, self).declare(env)
+        binary, stripped = super().declare(env)
 
         out_dir = env['GTEST_OUT_DIR']
         xml_file = out_dir.Dir(str(self.dir)).File(self.target + '.xml')
@@ -520,7 +520,7 @@ SimObject.fixed = True
 class SimpleModuleLoader(importlib.abc.Loader):
     '''A simple wrapper which delegates setting up a module to a function.'''
     def __init__(self, executor):
-        super(SimpleModuleLoader, self).__init__()
+        super().__init__()
         self.executor = executor
     def create_module(self, spec):
         return None
@@ -530,7 +530,7 @@ class SimpleModuleLoader(importlib.abc.Loader):
 
 class M5MetaPathFinder(importlib.abc.MetaPathFinder):
     def __init__(self, modules):
-        super(M5MetaPathFinder, self).__init__()
+        super().__init__()
         self.modules = modules
         self.installed = set()