Updated to pybench 2.0.

See svn.python.org/external/pybench-2.0 for the original import of that
version.

Note that platform.py was not copied over from pybench-2.0 since
it is already part of Python 2.5.
diff --git a/Tools/pybench/Constructs.py b/Tools/pybench/Constructs.py
index 00045bd..5105461 100644
--- a/Tools/pybench/Constructs.py
+++ b/Tools/pybench/Constructs.py
@@ -2,7 +2,7 @@
 
 class IfThenElse(Test):
 
-    version = 0.31
+    version = 2.0
     operations = 30*3 # hard to say...
     rounds = 150000
 
@@ -469,9 +469,9 @@
 
 class NestedForLoops(Test):
 
-    version = 0.3
+    version = 2.0
     operations = 1000*10*5
-    rounds = 150
+    rounds = 300
 
     def test(self):
 
@@ -494,9 +494,9 @@
 
 class ForLoops(Test):
 
-    version = 0.1
+    version = 2.0
     operations = 5 * 5
-    rounds = 8000
+    rounds = 10000
 
     def test(self):