[tsan] Replace pthread semaphore in signal_cond.cc with barrier_wait

[kubamracek]

Summary

Pthread semaphores are not available on OS X. Let's replace sem_wait/sem_post with barrier_wait, which makes the test pass on OS X. I know that sem_wait/sem_post is intercepted by TSan, whereas barrier_wait is TSan-invisible, but the purpose of the test is not affected by this.

Also, let's properly initialize the mutex and cond variables.

compiler-rt/trunk/test/tsan/signal_cond.cc

 // RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
 #include "test.h"
 #include <signal.h>
 #include <unistd.h>
 #include <errno.h>
 #include <semaphore.h>
 
 // Test that signals can be delivered to blocked pthread_cond_wait.
 // https://code.google.com/p/thread-sanitizer/issues/detail?id=91
 
 int g_thread_run = 1;
 pthread_mutex_t mutex;
 pthread_cond_t cond;
-sem_t sem;
 
 void sig_handler(int sig) {
   (void)sig;
   write(1, "SIGNAL\n", sizeof("SIGNAL\n") - 1);
-  sem_post(&sem);
+  barrier_wait(&barrier);
 }
 
 void* my_thread(void* arg) {
   pthread_mutex_lock(&mutex);
   while (g_thread_run)
     pthread_cond_wait(&cond, &mutex);
   pthread_mutex_unlock(&mutex);
   return 0;
 }
 
 int main() {
-  sem_init(&sem, 0, 0);
+  barrier_init(&barrier, 2);
+
+  pthread_mutex_init(&mutex, 0);
+  pthread_cond_init(&cond, 0);
+
   signal(SIGUSR1, &sig_handler);
   pthread_t thr;
   pthread_create(&thr, 0, &my_thread, 0);
   // wait for thread to get inside pthread_cond_wait
   // (can't use barrier_wait for that)
   sleep(1);
   pthread_kill(thr, SIGUSR1);
-  while (sem_wait(&sem) == -1 && errno == EINTR) {
-  }
+  barrier_wait(&barrier);
   pthread_mutex_lock(&mutex);
   g_thread_run = 0;
   pthread_cond_signal(&cond);
   pthread_mutex_unlock(&mutex);
   pthread_join(thr, 0);
   fprintf(stderr, "DONE\n");
   return 0;
 }
 
 // CHECK: SIGNAL
 // CHECK: DONE