Python builtin hashfunc closure fix

If the wrong return type in the hash function was used, an error:
  SystemError: error return without exception set
was raised

Add some tests for testing builtin slots

Examples/test-suite/python/python_builtin_runme.py

@@ -0,0 +1,26 @@
+from python_builtin import *
+
+if is_python_builtin():
+  # Test 1 for tp_hash
+  if hash(SimpleValue(222)) != 222:
+    raise RuntimeError("tp_hash not working")
+
+  # Test 2 for tp_hash
+  try:
+    # Was incorrectly raising: SystemError: error return without exception set
+    h = hash(BadHashFunctionReturnType())
+    raise RuntimeError("Missing TypeError")
+  except TypeError:
+    pass
+
+  # Test 3 for tp_hash
+  passed = False
+  try:
+    h = hash(ExceptionHashFunction())
+  except RuntimeError, e:
+    passed = str(e).find("oops") != -1
+    pass
+
+  if not passed:
+    raise RuntimeError("did not catch exception in hash()")
+