Make chrome_browser_tests work with irt=0 again

tests/manifest_file/nacl.scons

 # -*- python -*-
 # Copyright (c) 2011 The Native Client 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('env')
 
 srpc_mf_obj = env.ComponentObject('srpc_manifest_file_test.o',
                                   'srpc_manifest_file_test.c')
 srpc_mf_nexe_name = 'srpc_manifest_file_test_%s' % env.get('TARGET_FULLARCH')
 srpc_mf_nexe = env.ComponentProgram(srpc_mf_nexe_name,
                                     srpc_mf_obj,
                                     EXTRA_LIBS=[
                                         'srpc',
                                         'platform',
                                         'gio',
                                         'imc',
                                         'imc_syscalls',
-                                        'pthread',
+                                        '${PTHREAD_LIBS}',
                                         '${NON_PPAPI_BROWSER_LIBS}'])
 env.Publish(srpc_mf_nexe_name, 'run',
             ['srpc_manifest_file_test.html',
              'srpc_manifest_file.nmf'])
 
 # chrome_browser_tests
 
 node = env.PPAPIBrowserTester(
     'srpc_mf_browser_test.out',
     url='srpc_manifest_file_test.html',
@@ skipping 76 matching lines @@
     files=env.ExtractPublishedFiles(pm_pi_mf_nexe_name),
     args=['--debug'],
 #    osenv=['NACLVERBOSITY=4,pp_weak_ref=4,weak_ref=4']
     )
 
 if not env.Bit('irt'):
   env.AddNodeToTestSuite(node,
                          ['chrome_browser_tests'],
                          'run_pm_pi_manifest_file_chrome_browser_test',
                          is_broken=env.PPAPIBrowserTesterIsBroken())