Use NSS_DISABLE_UNLOAD in valgrind and heapcheck scripts to avoid unsymbolized backtraces.

tools/heapcheck/heapcheck_test.py

 #!/usr/bin/python
-# Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+# Copyright (c) 2011 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.
 
 # heapcheck_test.py
 
 """Wrapper for running the test under heapchecker and analyzing the output."""
 
 import datetime
 import logging
 import os
@@ skipping 24 matching lines @@
     os.putenv(env_name, env_value)
     logging.info('export %s=%s', env_name, env_value)
 
   def Execute(self):
     """Executes the app to be tested."""
     logging.info('starting execution...')
     proc = ['sh', path_utils.ScriptDir() + '/heapcheck_std.sh']
     proc += self._args
     self.PutEnvAndLog('G_SLICE', 'always-malloc')
     self.PutEnvAndLog('NSS_DISABLE_ARENA_FREE_LIST', '1')
+    self.PutEnvAndLog('NSS_DISABLE_UNLOAD', '1')
     self.PutEnvAndLog('GTEST_DEATH_TEST_USE_FORK', '1')
     self.PutEnvAndLog('HEAPCHECK', self._mode)
     self.PutEnvAndLog('HEAP_CHECK_MAX_LEAKS', '-1')
     self.PutEnvAndLog('KEEP_SHADOW_STACKS', '1')
     self.PutEnvAndLog('PPROF_PATH',
         path_utils.ScriptDir() +
         '/../../third_party/tcmalloc/chromium/src/pprof')
     self.PutEnvAndLog('LD_PRELOAD', '/usr/lib/debug/libstdc++.so')
 
     common.RunSubprocess(proc, self._timeout)
@@ skipping 149 matching lines @@
                  'http://dev.chromium.org/developers/how-tos/'
                  'using-the-heap-leak-checker')
     return retcode
 
 
 def RunTool(args, supp_files, module):
   tool = HeapcheckWrapper(supp_files)
   MODULES_TO_SANITY_CHECK = ["base"]
   check_sanity = module in MODULES_TO_SANITY_CHECK
   return tool.Main(args[1:], check_sanity)