Add nacl-clang testing to SCons

tests/threads/race_test.c

 /*
  * Copyright (c) 2012 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.
  */
 
 #include <assert.h>
 #include <pthread.h>
 #include <semaphore.h>
 #include <stdio.h>
@@ skipping 32 matching lines @@
   }
   for (i = 0; i < n; i++) {
     pthread_join(t[i], NULL);
   }
 }
 
 /* Don't let various optimizations (e.g. tail call elimination) to happen. */
 NOINLINE void break_optimization(void) {
 #if defined(__pnacl__)
   volatile int foo;
   foo = 0;

[jvoung (off chromium), 2014/10/08 22:40:23]

Could just make this one case w/out __asm__?

[Derek Schuff, 2014/10/09 16:55:42]

I dunno, an asm seems like a lot more reliable way to defeat the optimizer if
you can have it.
Oh and gcc 4.8 warns on this that foo is set but not used. So we should just
keep it I think.

 #else
-  asm volatile ("");
+  __asm__ volatile ("");
 #endif
 }
 
 /* -------------------------------------------------------------------------- */
 /* positive_race_on_global_test
    Simle race on a global variable between three threads.
    We have few stack frames here to test ThreadSanitizer's output. */
 int simple_race_obj;
 NOINLINE void simple_race_write_frame_2(void) {
   break_optimization();
@@ skipping 167 matching lines @@
 /* -------------------------------------------------------------------------- */
 int main(void) {
   if (1) positive_race_on_global_test();
   if (1) positive_race_on_heap_test();
   if (1) positive_wrong_lock_test();
   if (1) negative_locked_access_test();
   if (1) negative_posix_sem_test();
   if (1) thread_create_and_join_test();
   return 0;
 }