Fix missing printf argument.

Change-Id: Ifd1eebfbcefa06570882da54a1c410eabf26bce7
diff --git a/core/jni/android_net_NetUtils.cpp b/core/jni/android_net_NetUtils.cpp
index 2ba8e8c..e97d61e 100644
--- a/core/jni/android_net_NetUtils.cpp
+++ b/core/jni/android_net_NetUtils.cpp
@@ -118,7 +118,7 @@
     result = ::dhcp_get_results(nameStr, ipaddr, gateway, &prefixLength,
             dns, server, &lease, vendorInfo, domains, mtu);
     if (result != 0) {
-        ALOGD("dhcp_get_results failed : %s (%s)", nameStr);
+        ALOGD("dhcp_get_results failed : %s (%s)", nameStr, ::dhcp_get_errmsg());
     }
 
     env->ReleaseStringUTFChars(ifname, nameStr);