persistent 4.0.9 hashes on 32-bit

[Jerry James]

The latest release of persistent, 4.0.9, fails some of its tests on 32-bit systems:

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FAIL: test_hash_equal (persistent.tests.test_timestamp.PyAndCComparisonTests)
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Traceback (most recent call last):
  File "/builddir/build/BUILD/python-persistent-4.0.9/persistent-4.0.9/persistent/tests/test_timestamp.py", line 254, in test_hash_equal
    self.assertEqual(hash(c), hash(py))
AssertionError: -1419374591 != 1979033151
======================================================================
FAIL: test_hash_equal_constants (persistent.tests.test_timestamp.PyAndCComparisonTests)
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Traceback (most recent call last):
  File "/builddir/build/BUILD/python-persistent-4.0.9/persistent-4.0.9/persistent/tests/test_timestamp.py", line 272, in test_hash_equal_constants
    self.assertEqual(hash(c), 1000006000001)
AssertionError: -721379967 != 1000006000001L
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This is because timestamp hash codes are the same size as a C long, but the code assumes they are 64 bits in some places. The attached patch fixes the issue.