Redirect addr2line error output to /dev/null.

tools/valgrind/asan/asan_symbolize.py

 #!/usr/bin/env python
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import os
 import re
 import sys
 import string
@@ skipping 14 matching lines @@
 # TODO(glider): need some refactoring here
 def symbolize_addr2line(line):
   #0 0x7f6e35cf2e45  (/blah/foo.so+0x11fe45)
   match = re.match('^( *#([0-9]+) *0x[0-9a-f]+) *\((.*)\+(0x[0-9a-f]+)\)', line)
   if match:
     frameno = match.group(2)
     binary = match.group(3)
     addr = match.group(4)
     if not pipes.has_key(binary):
       pipes[binary] = subprocess.Popen(["addr2line", "-f", "-e", binary],
-                         stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+                         stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+                         stderr=open(os.devnull, 'w'))
     p = pipes[binary]
     try:
       print >>p.stdin, addr
       function_name = p.stdout.readline().rstrip()
       file_name     = p.stdout.readline().rstrip()
     except:
       function_name = ""
       file_name = ""
     file_name = fix_filename(file_name)
 
@@ skipping 104 matching lines @@
     for line in sys.stdin:
       if system == 'Linux':
         symbolize_addr2line(line)
       elif system == 'Darwin':
         symbolize_atos(line)
   else:
     print 'Unknown system: ', system
 
 if __name__ == '__main__':
   main()