Get rid of assumptions about ".nexe" extension.

tests/egyptian_cotton/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 os
 
 Import('env')
 
 env.Replace(EXTRA_LIBS=['pthread'])
 
-env.ComponentProgram('egyptian_cotton.nexe', 'egyptian_cotton.c')
+egyptian_cotton_nexe = env.ComponentProgram('egyptian_cotton',
+                                            'egyptian_cotton.c')
 
 platform_limits_known = False
 
 # this test accepts the number of threads to attempt to create as an
 # argument. NACL_THREAD_MAX is 8192 for x86-32 and x86-64, and 4096
 # for the Arm.  See the header files
 # src/trusted/service_runtime/arch/{x86,arm}/sel_ldr_{x86,arm}.h for
 # the current values (and update this comment to reflect reality!).
 # On the x86_32, the actual number of threads possible is slightly
 # fewer than 8192, since the service runtime's trusted internal
@@ skipping 89 matching lines @@
 # TODO(bsy): figure out why this fails on atom64 with 1GB RAM.
 # Disable thread_stack_alloc_test on one specific atom64 box.
 if os.environ.get('COMPUTERNAME') == 'NACL-ATOM1':
   tests = [t for t in tests if t[0] != 'thread_stack_alloc_test']
 
 # This test does not make much sense on Valgrind, and is too slow.
 if env.IsRunningUnderValgrind():
   tests = [t for t in tests if t[0] != 'thread_stack_alloc_test']
 
 def ThreadTestNode(name, args):
-  cmd = [env.File('egyptian_cotton.nexe')] + args
-  return env.CommandSelLdrTestNacl(name + '.out', command = cmd)
+  return env.CommandSelLdrTestNacl(name + '.out',
+                                   egyptian_cotton_nexe,
+                                   args=args)
 
 nodes = [ ThreadTestNode(name, args) for name, args in tests ]
 
 is_broken = env.Bit('target_arm') and env.UsingEmulator()
 for p, n in zip(tests, nodes):
   env.AddNodeToTestSuite(n, ['small_tests', 'sel_ldr_tests'], 'run_' + p[0],
                          is_broken=is_broken)