COMPAT: 32-bit indexers compat (#18122)

xref #17755

Author: jreback

pandas/tests/indexes/period/test_indexing.py

@@ -499,8 +499,8 @@ def test_get_indexer_non_unique(self):
         idx2 = pd.PeriodIndex([p2, p1, p3, p4])
 
         result = idx1.get_indexer_non_unique(idx2)
-        expected_indexer = np.array([1, 0, 2, -1, -1], dtype=np.int64)
-        expected_missing = np.array([2, 3], dtype=np.int64)
+        expected_indexer = np.array([1, 0, 2, -1, -1], dtype=np.intp)
+        expected_missing = np.array([2, 3], dtype=np.intp)
 
         tm.assert_numpy_array_equal(result[0], expected_indexer)
         tm.assert_numpy_array_equal(result[1], expected_missing)