Add sanity test for CPU profiler

src/platform-freebsd.cc

Index: src/platform-freebsd.cc
diff --git a/src/platform-freebsd.cc b/src/platform-freebsd.cc
index 14f7171a3cf7f33fb349bff7a65ad3d978ed117e..8c2e397ebad71ce955ca04a4c2777a9839bd909f 100644
--- a/src/platform-freebsd.cc
+++ b/src/platform-freebsd.cc
@@ -500,7 +500,8 @@ class Thread::PlatformData : public Malloced {
 
 Thread::Thread(const Options& options)
     : data_(new PlatformData),
-      stack_size_(options.stack_size()) {
+      stack_size_(options.stack_size()),
+      start_semaphore_(NULL) {
   set_name(options.name());
 }
 
@@ -517,7 +518,7 @@ static void* ThreadEntry(void* arg) {
   // one) so we initialize it here too.
   thread->data()->thread_ = pthread_self();
   ASSERT(thread->data()->thread_ != kNoThread);
-  thread->Run();
+  thread->NotifyStartedAndRun();
   return NULL;
 }
 
@@ -765,7 +766,7 @@ class SignalSender : public Thread {
 
       // Start a thread that sends SIGPROF signal to VM threads.
       instance_ = new SignalSender(sampler->interval());
-      instance_->Start();
+      instance_->StartSynchronously();
     } else {
       ASSERT(instance_->interval_ == sampler->interval());
     }