libsysutils: add some rudimentary tests

Test: atest libsysutils_tests
Change-Id: I3aa44c5af821c3161cf598b86216480d2424d336
diff --git a/libsysutils/Android.bp b/libsysutils/Android.bp
index 3a12292..29d23c8 100644
--- a/libsysutils/Android.bp
+++ b/libsysutils/Android.bp
@@ -27,3 +27,16 @@
 
     export_include_dirs: ["include"],
 }
+
+cc_test {
+    name: "libsysutils_tests",
+    test_suites: ["device-tests"],
+    srcs: [
+        "src/SocketListener_test.cpp",
+    ],
+    shared_libs: [
+        "libbase",
+        "libcutils",
+        "libsysutils",
+    ],
+}