BannedFilesTest: Add "sync_agent"

Change-Id: I0b737ac4f855cd190cc7f7a09a780301e43c37e0
diff --git a/tests/tests/security/src/android/security/cts/BannedFilesTest.java b/tests/tests/security/src/android/security/cts/BannedFilesTest.java
index 017bac0..b4deed5 100644
--- a/tests/tests/security/src/android/security/cts/BannedFilesTest.java
+++ b/tests/tests/security/src/android/security/cts/BannedFilesTest.java
@@ -22,6 +22,10 @@
 
 public class BannedFilesTest extends TestCase {
 
+    public void testNoSyncAgent() {
+        assertNotSetugid("/system/bin/sync_agent");
+    }
+
     /**
      * setuid or setgid "ip" command can be used to modify the
      * routing tables of a device, potentially allowing a malicious