Use native code to convert strings to IP addresses.

1. Add an ipStringToByteArray method to the OSNetworkSystem interface and
   provide a native implementation for it.
2. Change InetAddress to use the new method.
3. Remove  a mid-sized chunk of Inet6Util, which is now redundant.
4. Remove the KnownFailure annotations from the InetAddress, InetAddress and
   Inet6Address tests that expected 1.2.3, 1.3 and 3 to be valid IPv4
   addresses. These tests now pass again.
5. Removed an unused native method.
6. Added a comment to the top of the native socket implementation to the effect
   that the file is significantly different from harmony.

Change-Id: I3665f82b00ebc089e9133cc6166dda5a99fa10e4
8 files changed