tests/internal_bench/var: Benchmark ordered map accesses.

This adds an internal_bench benchmark that benchmarks ordered map linear
scan cache performance.

Signed-off-by: Anson Mansfield <amansfield@mantaro.com>

tests/internal_bench/var-6.6-instance-builtin_ordered.py

@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    i = 0
+    o = set()  # object with largest rom-frozen ordered locals_dict
+    n = "__contains__"  # last element in that dict for longest lookup
+    while i < num:
+        i += hasattr(o, n)  # True, converts to 1
+
+
+bench.run(test)