Track changes to Posix.* API.

We need to flip() the byte buffer before attempting to read
the data written to it.

bug: 18641009

(cherry picked from commit 96f656c39edf5983ce0bb8f6d5f9c0f1ac761507)

Change-Id: Ib796fafa1e4cf81351245fff6763ce17924acde9
diff --git a/tests/cts/net/src/android/net/ipv6/cts/PingTest.java b/tests/cts/net/src/android/net/ipv6/cts/PingTest.java
index 49fc59c..e9bfb43 100644
--- a/tests/cts/net/src/android/net/ipv6/cts/PingTest.java
+++ b/tests/cts/net/src/android/net/ipv6/cts/PingTest.java
@@ -130,6 +130,7 @@
 
         // Check the response is an echo reply.
         byte[] response = new byte[bytesRead];
+        responseBuffer.flip();
         responseBuffer.get(response, 0, bytesRead);
         assertEquals((byte) 0x81, response[0]);