Rename translation units containing main() to main.cpp

Also unify style of argv declaration

Change-Id: I1dcb8689b1cd38e042a0b1f05be7f98bd2d487ed
diff --git a/tools/ping/server/ndn-ping-server.cpp b/tools/ping/server/main.cpp
similarity index 98%
rename from tools/ping/server/ndn-ping-server.cpp
rename to tools/ping/server/main.cpp
index 28c6871..9aa7261 100644
--- a/tools/ping/server/ndn-ping-server.cpp
+++ b/tools/ping/server/main.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2015-2018, Arizona Board of Regents.
+ * Copyright (c) 2015-2019, Arizona Board of Regents.
  *
  * This file is part of ndn-tools (Named Data Networking Essential Tools).
  * See AUTHORS.md for complete list of ndn-tools authors and contributors.
@@ -187,7 +187,7 @@
 } // namespace ndn
 
 int
-main(int argc, char** argv)
+main(int argc, char* argv[])
 {
   return ndn::ping::server::main(argc, argv);
 }