tests: Fix compilation errors because of changes ndn-cxx library

Change-Id: I10fb7eb366a03c2e06e6d2efefdde8a9dd0da724
Refs: #2951
diff --git a/tests/core/segment-publisher.t.cpp b/tests/core/segment-publisher.t.cpp
index e0f8e40..b72c198 100644
--- a/tests/core/segment-publisher.t.cpp
+++ b/tests/core/segment-publisher.t.cpp
@@ -73,7 +73,7 @@
     size_t totalLength = 0;
     for (int64_t i = 0; i < N; i++)
       {
-        totalLength += ndn::prependNonNegativeIntegerBlock(outBuffer, tlv::Content, i);
+        totalLength += prependNonNegativeIntegerBlock(outBuffer, tlv::Content, i);
       }
     m_totalPayloadLength += totalLength;
     return totalLength;