Rename translation units containing main() to main.cpp

Also unify style of argv declaration

Change-Id: I1dcb8689b1cd38e042a0b1f05be7f98bd2d487ed
diff --git a/tools/peek/ndnpeek/main.cpp b/tools/peek/ndnpeek/main.cpp
index f04cec4..428634a 100644
--- a/tools/peek/ndnpeek/main.cpp
+++ b/tools/peek/ndnpeek/main.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2019,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -171,7 +171,7 @@
 } // namespace ndn
 
 int
-main(int argc, char** argv)
+main(int argc, char* argv[])
 {
   return ndn::peek::main(argc, argv);
 }