Use the documented 5 line prolog in every sample application. Tidy up sample prologs and header code.

samples/exiv2json.cpp

@@ -1,4 +1,22 @@
 // ***************************************************************** -*- C++ -*-
+/*
+ * Copyright (C) 2004-2021 Exiv2 authors
+ * This program is part of the Exiv2 distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA.
+ */
 // exiv2json.cpp
 // Sample program to print metadata in JSON format
 
@@ -12,7 +30,6 @@
 #include <map>
 #include <vector>
 #include <set>
-
 #include <cstdlib>
 #include <limits.h>
 #include <sys/types.h>
@@ -270,6 +287,9 @@ int main(int argc, char* const argv[])
 {
     Exiv2::XmpParser::initialize();
     ::atexit(Exiv2::XmpParser::terminate);
+#ifdef EXIV2_ENABLE_BMFF
+    Exiv2::enableBMFF();
+#endif
 
     try {
         if (argc < 2 || argc > 3) {