repo: fix config max-packets from int to uint64_t

refs #2736

Change-Id: I19471dd999081042457c0364cd6bef7b9ffe8e4d
diff --git a/src/repo.hpp b/src/repo.hpp
index 3e7e89d..754a63c 100644
--- a/src/repo.hpp
+++ b/src/repo.hpp
@@ -45,7 +45,7 @@
   std::vector<ndn::Name> dataPrefixes;
   std::vector<ndn::Name> repoPrefixes;
   std::vector<std::pair<std::string, std::string> > tcpBulkInsertEndpoints;
-  int64_t nMaxPackets;
+  uint64_t nMaxPackets;
   boost::property_tree::ptree validatorNode;
 };