Get rid of assumptions about ".nexe" extension.

tests/ppapi_browser/bad/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.
 #
 # Manual testing with localhost:5103/scons-out/.../staging/ppapi_bad.html:
 #   scons --mode=nacl ppapi_bad
 # Automatic testing:
 #   scons run_ppapi_bad_browser_test
 #
@@ skipping 12 matching lines @@
   env.File('${SCONSTRUCT_DIR}/tests/ppapi_browser/progress_events/' +
            'ppapi_progress_events.js'),
   env.File('${SCONSTRUCT_DIR}/tools/browser_tester/browserdata/nacltest.js')
   ]
 ppapi_bad = env.Replicate('${STAGING_DIR}', ppapi_bad_files)
 
 
 # Compile all nexes embedded into the above html
 for kind in [ 'ppp_initialize', 'no_ppp_instance', 'ppp_instance_didcreate' ]:
   bad_nmf = 'ppapi_bad_%s.nmf' % kind
-  bad_nexe = ('ppapi_bad_%s_%s.nexe' % (kind, env.get('TARGET_FULLARCH')))
+  bad_nexe = ('ppapi_bad_%s_%s' % (kind, env.get('TARGET_FULLARCH')))
   env.ComponentProgram(bad_nexe,
                        ['ppapi_bad_%s.cc' % kind],
                        EXTRA_LIBS=['${PPAPI_LIBS}',
                                    'platform',
                                    'pthread',
                                    'gio'])
 
   env.Publish(bad_nexe, 'run', [bad_nmf])
   ppapi_bad_files.extend(env.ExtractPublishedFiles(bad_nexe))
   env.Depends(ppapi_bad, env.Alias(bad_nexe))
 
 # "scons --mode=nacl ppapi_bad" will publish the html and all of its
 # dependencies to scons-out.
 env.Alias('ppapi_bad', ppapi_bad)
 
 node = env.PPAPIBrowserTester(
     'ppapi_bad_browser_test.out',
     url='ppapi_bad.html',
     files=[ env.File(f) for f in ppapi_bad_files ],
     args=['--allow_404'])
 
 env.AddNodeToTestSuite(node,
                        ['chrome_browser_tests'],
                        'run_ppapi_bad_browser_test',
                        is_broken=env.PPAPIBrowserTesterIsBroken())