daemon: print peers' top height in sync_info

src/cryptonote_protocol/cryptonote_protocol_defs.h

@@ -76,6 +76,8 @@ namespace cryptonote
 
 	boost::uuids::uuid connection_id;
 
+    uint64_t height;
+
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(incoming)
       KV_SERIALIZE(localhost)
@@ -97,6 +99,7 @@ namespace cryptonote
       KV_SERIALIZE(current_upload)
       KV_SERIALIZE(support_flags)
       KV_SERIALIZE_VAL_POD_AS_BLOB(connection_id)
+      KV_SERIALIZE(height)
     END_KV_SERIALIZE_MAP()
   };