Add nacl-clang testing to SCons

tests/compiler_thread_suspension/nacl.scons

 # -*- python -*-
 # Copyright (c) 2013 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')
 
 # PNaCl doesn't have -finstrument-for-thread-suspension currently
 # BUG http://code.google.com/p/nativeclient/issues/detail?id=2363
 # Neither does next-generation GCC, so far extant only for ARM (and the
 # only non-bitcode compiler for ARM).
-if env.Bit('bitcode') or env.Bit('target_arm'):
+if env.Bit('bitcode') or env.Bit('target_arm') or env.Bit('nacl_clang'):
   Return()
 
 inputs = ['gc_noinst.c']
 
 # Compile gc_inst.c with -finstrument-for-thread-suspension
 env_inst = env.Clone()
 env_inst.Append(CFLAGS=['-finstrument-for-thread-suspension'])
 inputs += env_inst.ComponentObject('gc_inst.c')
 
 nexe = env.ComponentProgram('compiler_thread_suspension', inputs,
                             EXTRA_LIBS=['${NONIRT_LIBS}'])
 
 node = env.CommandSelLdrTestNacl('compiler_thread_suspension.out', nexe)
 
 env.AddNodeToTestSuite(node, ['small_tests'],
                        'run_compiler_thread_suspension_test')