Automatically run scudo unit tests.

Test: Ran atest --test-mapping external/scudo/TEST_MAPPING
Change-Id: I4673377b742774adb92503744dca45c2aeca3069
diff --git a/TEST_MAPPING b/TEST_MAPPING
new file mode 100644
index 0000000..287b24e
--- /dev/null
+++ b/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "scudo_unit_tests"
+    }
+  ]
+}