Introduce fwmarkd: a service to set the fwmark of sockets.

(cherry picked from commit d5121e212c1f53b1cb6458ee83be892d94fdfef3)

Change-Id: Ieb049fe34ea2b21a7f6108f2099d1a8b8f2c28f7
diff --git a/rootdir/init.rc b/rootdir/init.rc
index e289a02..ed756e0 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -491,6 +491,7 @@
     socket netd stream 0660 root system
     socket dnsproxyd stream 0660 root inet
     socket mdns stream 0660 root system
+    socket fwmarkd stream 0660 root inet
 
 service debuggerd /system/bin/debuggerd
     class main