set timeout in cfg

tests/filecheck/lit.cfg

@@ -6,3 +6,17 @@ config.test_source_root = os.path.dirname(__file__)
 config.name = "asl-xdsl"
 config.test_format = lit.formats.ShTest()
 config.suffixes = ['.asl', '.mlir']
+
+# checking if maxIndividualTestTime is available on the platform and sets
+# it to 20sec if so, declares lit-max-individual-test-time feature for
+# further checking by tests.
+supported, errormsg = lit_config.maxIndividualTestTimeIsSupported
+if supported:
+    config.available_features.add("lit-max-individual-test-time")
+    lit_config.maxIndividualTestTime = 20
+else:
+    lit_config.warning(
+        "Setting a timeout per test not supported. "
+        + errormsg
+        + " Some tests will be skipped."
+    )