Fix libcore buildbot failure.

... due to a duplicate suppression. test_PacketSocketAddress has been
moved to libcore/knownfailures.txt.

Change-Id: I5c9cc98938d46607cba5a799e9c45b864ec22bf8
diff --git a/tools/libcore_failures.txt b/tools/libcore_failures.txt
index 8ce19dd..a8bc4e1 100644
--- a/tools/libcore_failures.txt
+++ b/tools/libcore_failures.txt
@@ -109,12 +109,6 @@
   bug: 19165288
 },
 {
-  description: "Needs to be run as root",
-  result: EXEC_FAILED,
-  modes: [host],
-  names: ["libcore.io.OsTest#test_PacketSocketAddress"]
-},
-{
   description: "Needs kernel updates on host/device",
   result: EXEC_FAILED,
   names: ["libcore.io.OsTest#test_socketPing"]