Get rid of manual int->ipv4 string generation

bug:2542681
Change-Id: I67919d7b5dc8d72eeb2dfb9e3906210b1951d4fb
diff --git a/core/java/android/net/DhcpInfo.java b/core/java/android/net/DhcpInfo.java
index 9c81c19..e2660e4 100644
--- a/core/java/android/net/DhcpInfo.java
+++ b/core/java/android/net/DhcpInfo.java
@@ -18,6 +18,7 @@
 
 import android.os.Parcelable;
 import android.os.Parcel;
+import java.net.InetAddress;
 
 /**
  * A simple object for retrieving the results of a DHCP request.
@@ -65,10 +66,7 @@
     }
 
     private static void putAddress(StringBuffer buf, int addr) {
-        buf.append(addr  & 0xff).append('.').
-            append((addr >>>= 8) & 0xff).append('.').
-            append((addr >>>= 8) & 0xff).append('.').
-            append((addr >>>= 8) & 0xff);
+        buf.append(NetworkUtils.intToInetAddress(addr).getHostAddress());
     }
 
     /** Implement the Parcelable interface {@hide} */