fw: silence unused variable warning in FaceTable

Change-Id: I32136aabbac6c25f3b1e4ea17e2eeaddafd5c8c0
diff --git a/daemon/fw/face-table.cpp b/daemon/fw/face-table.cpp
index 3e848e8..07409c6 100644
--- a/daemon/fw/face-table.cpp
+++ b/daemon/fw/face-table.cpp
@@ -79,7 +79,7 @@
 {
   face->setId(faceId);
   auto ret = m_faces.emplace(faceId, face);
-  BOOST_ASSERT(ret.second);
+  BOOST_VERIFY(ret.second);
 
   NFD_LOG_INFO("Added face id=" << faceId <<
                " remote=" << face->getRemoteUri() <<