Update torch xfails for functions that don't support complex numbers

Author: asmeurer

torch-xfails.txt

@@ -186,3 +186,10 @@ array_api_tests/test_statistical_functions.py::test_var
 # 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
+
+# These functions do not yet support complex numbers
+array_api_tests/test_operators_and_elementwise_functions.py::test_sign
+array_api_tests/test_operators_and_elementwise_functions.py::test_expm1
+array_api_tests/test_operators_and_elementwise_functions.py::test_round
+array_api_tests/test_set_functions.py::test_unique_counts
+array_api_tests/test_set_functions.py::test_unique_values