Get rid of assumptions about ".nexe" extension.

tests/memcheck_test/nacl.scons

 # -*- python -*-
 # Copyright 2010 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')
 
 # tests in this directory contain (inline) assembler
 if env.Bit('bitcode'):
   Return()
 
 if not env.IsRunningUnderValgrind():
   Return()
 
 if env.Bit('nacl_glibc'):
   golden = env.File('memcheck_test.glibc.stderr.golden')
 else:
   golden = env.File('memcheck_test.stderr.golden')
 
-env.ComponentProgram('memcheck_test.nexe', 'memcheck_test.c')
+memcheck_test_nexe = env.ComponentProgram('memcheck_test', 'memcheck_test.c')
 node = env.CommandSelLdrTestNacl(
     'memcheck_test.out',
-    command=[env.File('memcheck_test.nexe')],
+    memcheck_test_nexe,
     stderr_golden=golden,
     filter_group_only='true',
     filter_regex=(
       "'(Invalid [a-z]+ of size .+)|"
       "( at )0x[01-9A-Fa-f]+: ([_a-zA-Z][_a-zA-Z01-9]+) [^ ]+:[01-9]+|"
       "( by )0x[01-9A-Fa-f]+: ([_a-zA-Z][_a-zA-Z01-9]+) [^ ]+:[01-9]+|"
       "( Address) 0x[01-9A-Fa-f]+( is.+)|"
       "( Conditional jump or move depends.+)|"
       "(VG_USERREQ__CLIENT_CALL.+)|"
       "( .*BACKTRACE:)|"
       "(ERROR SUMMARY: [01-9]+ errors from [01-9]+ contexts)|"
       "(strcmp: .*)'"),
     exit_status='1',
     )
 env.AddNodeToTestSuite(node, ['memcheck_bot_tests'], 'run_memcheck_test')
 
 
 # Leak checker sanity test.
 if env.Bit('with_leakcheck'):
-  env.ComponentProgram('leak_test.nexe', 'leak_test.c',
-                       EXTRA_LIBS=['pthread'])
+  leak_test_nexe = env.ComponentProgram('leak_test', 'leak_test.c',
+                                        EXTRA_LIBS=['pthread'])
   node = env.CommandSelLdrTestNacl(
       'leak_test.out',
-      command=[env.File('leak_test.nexe')],
+      leak_test_nexe,
       stderr_golden=env.File('leak_test.stderr.golden'),
       filter_group_only='true',
       filter_regex=(
           "'(7,931,147 bytes in 1 blocks are definitely lost).*'"),
       exit_status='1',
       )
   env.AddNodeToTestSuite(node, ['memcheck_bot_tests'], 'run_leak_test')