[fusl] Add llvm's lit tool to third_party

third_party/lit/tests/unittest-adaptor.py

Index: third_party/lit/tests/unittest-adaptor.py
diff --git a/third_party/lit/tests/unittest-adaptor.py b/third_party/lit/tests/unittest-adaptor.py
new file mode 100644
index 0000000000000000000000000000000000000000..0848cd22baae858309cccc782b8ebe31f735b065
--- /dev/null
+++ b/third_party/lit/tests/unittest-adaptor.py
@@ -0,0 +1,18 @@
+# Check the lit adaption to run under unittest.
+#
+# RUN: %{python} %s %{inputs}/unittest-adaptor 2> %t.err
+# RUN: FileCheck < %t.err %s
+#
+# CHECK-DAG: unittest-adaptor :: test-two.txt ... FAIL
+# CHECK-DAG: unittest-adaptor :: test-one.txt ... ok
+
+import unittest
+import sys
+
+import lit
+import lit.discovery
+
+input_path = sys.argv[1]
+unittest_suite = lit.discovery.load_test_suite([input_path])
+runner = unittest.TextTestRunner(verbosity=2)
+runner.run(unittest_suite)