Do not pollute global namespace with internal classes

Bug #64680
diff --git a/fofi/FoFiIdentifier.cc b/fofi/FoFiIdentifier.cc
index d8ee7e0..be28e25 100644
--- a/fofi/FoFiIdentifier.cc
+++ b/fofi/FoFiIdentifier.cc
@@ -6,6 +6,20 @@
 //
 //========================================================================
 
+//========================================================================
+//
+// Modified under the Poppler project - http://poppler.freedesktop.org
+//
+// All changes made under the Poppler project to this file are licensed
+// under GPL version 2 or later
+//
+// Copyright (C) 2013 Christoph Duelli <duelli@melosgmbh.de>
+//
+// To see a description of the changes please see the Changelog file that
+// came with your tarball or type make ChangeLog if you are building from git
+//
+//========================================================================
+
 #ifdef USE_GCC_PRAGMAS
 #pragma implementation
 #endif
@@ -18,6 +32,8 @@
 
 //------------------------------------------------------------------------
 
+namespace { // do not pollute global namespace
+
 class Reader {
 public:
 
@@ -413,6 +429,8 @@
   return gTrue;
 }
 
+}
+
 //------------------------------------------------------------------------
 
 static FoFiIdentifierType identify(Reader *reader);