Get rid of assumptions about ".nexe" extension.

tests/redir/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 atexit
 import os
 import tempfile
 
 Import('env')
 
-env.ComponentProgram('redir_test.nexe', 'redir_test.c')
+redir_test_nexe = env.ComponentProgram('redir_test', 'redir_test.c')
 
 # windows builds swallow stdout and stderr, so we cannot check
 # against the golden files when stdout and stderr are not redirected
 # to files.
 if not env.Bit('host_windows'):
   node = env.CommandSelLdrTestNacl(
       'redir_test_basic.out',
-      command=[env.File('redir_test.nexe')],
+      redir_test_nexe,
       stdout_golden=env.File('redir_test.stdout'),
       stderr_golden=env.File('redir_test.stderr'),
       filter_regex="'^REALOUTPUT'",
       )
 
   env.AddNodeToTestSuite(node,
                          ['small_tests', 'sel_ldr_tests'],
                          'run_redir_basic_test')
 
 # we immediately close to ensure that python is not holding on to a
@@ skipping 10 matching lines @@
       os.unlink(fname)
     except OSError:
       pass
   return Cleanup
 
 atexit.register(CleanupBinder(outfile))
 atexit.register(CleanupBinder(errfile))
 
 node = env.CommandSelLdrTestNacl(
     'redir_test.out',
-    command=[env.File('redir_test.nexe')],
+    redir_test_nexe,
     filter_regex="'^REALOUTPUT'",
     osenv=['NACL_EXE_STDOUT=%s' % outfile,
            'NACL_EXE_STDERR=%s' % errfile])
 
 env.AddNodeToTestSuite(node,
                        ['small_tests', 'sel_ldr_tests'],
                        'run_redir_test')
 
 node = env.Command('redir_test_output_compare',
                    ['${PYTHON}',
                     env.File('${SCONSTRUCT_DIR}/tools/file_cmp_test.py'),
                     outfile,
                     env.File('redir_test.stdout')],
                    [env.File(outfile)])
 
 env.AddNodeToTestSuite(node,
                        ['small_tests', 'sel_ldr_tests'],
                        'run_redir_test')