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 96f656c39e)

Change-Id: Ib796fafa1e4cf81351245fff6763ce17924acde9

tests/cts/net/src/android/net/ipv6/cts/PingTest.java

@@ -130,6 +130,7 @@ public class PingTest extends AndroidTestCase {
 
         // Check the response is an echo reply.
         byte[] response = new byte[bytesRead];
+        responseBuffer.flip();
         responseBuffer.get(response, 0, bytesRead);
         assertEquals((byte) 0x81, response[0]);