Support adding, deleting, and clearing IPv6 addrs.

- Provide a function to add and delete IPv4/IPv6 addresses
  using netlink.
- Provide a function that clears all IP addresses on an
  interface that can be used by netd.

Also, a couple of cleanups:

- Update the header file to match reality, and include the
  header file in the implementation. Also fix a caller that
  has an incorrect method signature.
- Fix whitespace in Android.mk.

Change-Id: Ifba9d60cdfffb0b7e5c3b9c6ab328f5f77d259c4
diff --git a/libnetutils/Android.mk b/libnetutils/Android.mk
index 1ef7da9..5f5849f 100644
--- a/libnetutils/Android.mk
+++ b/libnetutils/Android.mk
@@ -6,10 +6,10 @@
         dhcpmsg.c \
         dhcp_utils.c \
         ifc_utils.c \
-	packet.c
+        packet.c
 
 LOCAL_SHARED_LIBRARIES := \
-	libcutils
+        libcutils
 
 LOCAL_MODULE:= libnetutils