bug#5350: 23.1.91; error in c++-mode highlighting/indentation

Hi, this is a bugs somewhere in c-mode syntactic analyser (or so it
seems). It happens to me in several circumstances; below i describe a
simple instance for a C++ file (i've seen it happening also in pure C
files).

1) Start emacs with -nw and -Q
2) Create a new C++ file, say test.cpp
3) Insert the following text:

/* Copyright (C) 2009, 2100 Foo Industries */

#include <libPlasma/c++/Pool.h>

4) When pressing the closing '>' an error occurs with the following
backtrace:

Debugger entered--Lisp error: (args-out-of-range 79 80)
  put-text-property(79 80 category c-cpp-delimiter)
  byte-code("\306 \307\211\307\310\211\310\211
\310\311\216\312\211T\313\314$\210)\312\211T\313\314$\210.\310\207" [modified buffer-undo-list inhibit-read-only inhibit-point-motion-hooks before-change-functions after-change-functions buffer-modified-p t nil ((byte-code "\204