[pph] Fix template class tables streaming

gcc/cp/pt.c

 /* Handle parameterized types (templates) for GNU C++.
    Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
    2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
    Free Software Foundation, Inc.
    Written by Ken Raeburn (raeburn@cygnus.com) while at Watchmaker Computing.
    Rewritten by Jason Merrill (jason@cygnus.com).
 
 This file is part of GCC.
 
 GCC is free software; you can redistribute it and/or modify
@@ skipping 1630 matching lines @@
 bool
 reregister_specialization (tree spec, tree tinfo, tree new_spec)
 {
   spec_entry **slot;
   spec_entry elt;
 
   elt.tmpl = most_general_template (TI_TEMPLATE (tinfo));
   elt.args = TI_ARGS (tinfo);
   elt.spec = NULL_TREE;
 
-  slot = (spec_entry **) htab_find_slot (decl_specializations, &elt, INSERT);
-  if (*slot)
+  slot = (spec_entry **) htab_find_slot (decl_specializations, &elt, NO_INSERT);
+  if (slot && *slot)
     {
       gcc_assert ((*slot)->spec == spec || (*slot)->spec == new_spec);
       gcc_assert (new_spec != NULL_TREE);
       (*slot)->spec = new_spec;
       return 1;
     }
 
   return 0;
 }
 
@@ skipping 18703 matching lines @@
   pph_in_spec_entry_htab (stream, &decl_specializations);
   if (flag_pph_dump_tree)
     pph_dump_spec_entry_htab (pph_logfile, "decl", &decl_specializations);
   pph_in_spec_entry_htab (stream, &type_specializations);
   if (flag_pph_dump_tree)
     pph_dump_spec_entry_htab (pph_logfile, "type", &type_specializations);
 }
 
 
 #include "gt-cp-pt.h"