Update XFAILs

Author: asmeurer

numpy-1-21-xfails.txt

@@ -76,6 +76,10 @@ array_api_tests/test_set_functions.py::test_unique_counts
 array_api_tests/test_set_functions.py::test_unique_inverse
 array_api_tests/test_set_functions.py::test_unique_values
 
+# The test suite is incorrectly checking sums that have loss of significance
+# (https://github.com/data-apis/array-api-tests/issues/168)
+array_api_tests/test_statistical_functions.py::test_sum
+
 # NumPy 1.21 doesn't support NPY_PROMOTION_STATE=weak, so many tests fail with
 # type promotion issues
 array_api_tests/test_manipulation_functions.py::test_concat
@@ -149,8 +153,10 @@ array_api_tests/test_special_cases.py::test_binary[__mod__(x1_i is +0 and x2_i <
 array_api_tests/test_special_cases.py::test_binary[__mod__(x1_i is +0 and x2_i > 0) -> +0]
 array_api_tests/test_special_cases.py::test_binary[__mod__(x1_i is -0 and x2_i < 0) -> -0]
 array_api_tests/test_special_cases.py::test_binary[__mod__(x1_i is -0 and x2_i > 0) -> +0]
+array_api_tests/test_special_cases.py::test_binary[__pow__(abs(x1_i) < 1 and x2_i is +infinity) -> +0]
 array_api_tests/test_special_cases.py::test_binary[__pow__(abs(x1_i) < 1 and x2_i is -infinity) -> +infinity]
 array_api_tests/test_special_cases.py::test_binary[__pow__(abs(x1_i) > 1 and x2_i is +infinity) -> +infinity]
+array_api_tests/test_special_cases.py::test_binary[__pow__(abs(x1_i) > 1 and x2_i is -infinity) -> +0]
 array_api_tests/test_special_cases.py::test_binary[__pow__(x1_i < 0 and isfinite(x1_i) and isfinite(x2_i) and not x2_i.is_integer()) -> NaN]
 array_api_tests/test_special_cases.py::test_binary[__pow__(x1_i is +0 and x2_i < 0) -> +infinity]
 array_api_tests/test_special_cases.py::test_binary[__pow__(x1_i is +0 and x2_i > 0) -> +0]

numpy-xfails.txt

@@ -46,3 +46,7 @@ array_api_tests/test_special_cases.py::test_binary[__pow__(x1_i is -0 and x2_i >
 array_api_tests/test_special_cases.py::test_iop[__ipow__(x1_i is -infinity and x2_i > 0 and not (x2_i.is_integer() and x2_i % 2 == 1)) -> +infinity]
 array_api_tests/test_special_cases.py::test_iop[__ipow__(x1_i is -0 and x2_i > 0 and not (x2_i.is_integer() and x2_i % 2 == 1)) -> +0]
 array_api_tests/meta/test_hypothesis_helpers.py::test_symmetric_matrices
+
+# The test suite is incorrectly checking sums that have loss of significance
+# (https://github.com/data-apis/array-api-tests/issues/168)
+array_api_tests/test_statistical_functions.py::test_sum