rootdir: goldfish: Fix network route during emulation.

The net.eth0.gw system property is used by the ConnectivityService
to set the default route when it detects that 3G connectivity is
established. Because the property was undefined, the route was
unset which broke networking.

+ Format / document init.goldfish.sh

Change-Id: I1133cf6c093609300315cd0ea363c9e139b42521
diff --git a/rootdir/etc/init.goldfish.rc b/rootdir/etc/init.goldfish.rc
index fa70c2e..1ac09ca 100644
--- a/rootdir/etc/init.goldfish.rc
+++ b/rootdir/etc/init.goldfish.rc
@@ -6,6 +6,7 @@
 
 on boot
     setprop ARGH ARGH
+    setprop net.eth0.gw 10.0.2.2
     setprop net.eth0.dns1 10.0.2.3
     setprop net.gprs.local-ip 10.0.2.15
     setprop ro.radio.use-ppp no