tools: fix compilation for ubuntu 16.04

Change-Id: Ifdbc43994e0060b67ffb94a72fdac026671a3be2
diff --git a/tools/nlsrc.cpp b/tools/nlsrc.cpp
index aa02ed1..adeaeee 100644
--- a/tools/nlsrc.cpp
+++ b/tools/nlsrc.cpp
@@ -273,7 +273,7 @@
 void
 Nlsrc::fetchRtables()
 {
-  fetchFromRt<nlsr::RoutingTableStatus>([this] (const auto& rts) { recordRtable(rts); });
+  fetchFromRt<nlsr::RoutingTableStatus>([this] (const auto& rts) { this->recordRtable(rts); });
 }
 
 template <class T>