table/face: fix unused variable warnings in NameTree and NDNLP Slicer

refs #2290, #2287

Change-Id: I40f80f4c8a9fe830edafeada2bbd0b881194d0a3
diff --git a/daemon/face/ndnlp-slicer.cpp b/daemon/face/ndnlp-slicer.cpp
index 9efe7d6..6b5b818 100644
--- a/daemon/face/ndnlp-slicer.cpp
+++ b/daemon/face/ndnlp-slicer.cpp
@@ -118,7 +118,7 @@
     size_t pktSize = Slicer_encodeFragment(buffer,
       seqBlock[fragIndex], fragIndex, fragCount, payload, payloadSize);
 
-    BOOST_ASSERT(pktSize <= m_mtu);
+    BOOST_VERIFY(pktSize <= m_mtu);
 
     pa->push_back(buffer.block());
   }