tests/bench: Time namedtuple field access.

That's higher than instance field access - behold the power of hashing.

tests/bench/var-8-namedtuple-1st.py

@@ -0,0 +1,12 @@
+import bench
+from _collections import namedtuple
+
+T = namedtuple("Tup", "num bar")
+
+def test(num):
+    t = T(20000000, 0)
+    i = 0
+    while i < t.num:
+        i += 1
+
+bench.run(test)