Fix libnetutils to build with clean uapi headers.

(And old ones too.)

Bug: 11559337
Change-Id: Ie61218055bbe07655a9d53c539aa47b85098e42c
diff --git a/libnetutils/ifc_utils.c b/libnetutils/ifc_utils.c
index eb33d06..4d004f6 100644
--- a/libnetutils/ifc_utils.c
+++ b/libnetutils/ifc_utils.c
@@ -50,6 +50,11 @@
 #define ALOGW printf
 #endif
 
+#ifdef HAVE_ANDROID_OS
+/* SIOCKILLADDR is an Android extension. */
+#define SIOCKILLADDR 0x8939
+#endif
+
 static int ifc_ctl_sock = -1;
 static int ifc_ctl_sock6 = -1;
 void printerr(char *fmt, ...);