ril interface: Add support for User-User Signaling Information during call setup

Define the UUS data structures and add a pointer to it in RIL_Call for
MT Calls and RIL_Dial for MO calls. UUS information can be used to pass
the skypeId on some networks. Make the corresponding changes to
serialize and deserialize the data at the RIL interface.

Change-Id: Ibbd471cd062910fd4c365f76e809cfb224bd34a2
diff --git a/reference-ril/reference-ril.c b/reference-ril/reference-ril.c
index 65170fc..633ad8b 100644
--- a/reference-ril/reference-ril.c
+++ b/reference-ril/reference-ril.c
@@ -200,6 +200,8 @@
         if (err < 0) goto error;
     }
 
+    p_call->uusInfo = NULL;
+
     return 0;
 
 error: