Added a wait with timeout to the platform semaphore class

test/cctest/test-lock.cc

Index: test/cctest/test-lock.cc
===================================================================
--- test/cctest/test-lock.cc	(revision 1525)
+++ test/cctest/test-lock.cc	(working copy)
@@ -38,3 +38,26 @@
   CHECK_EQ(0, mutex->Unlock());
   delete mutex;
 }
+
+
+TEST(SemaphoreTimeout) {
+  bool ok;
+  Semaphore* sem = OS::CreateSemaphore(0);
+
+  // Semaphore not signalled - timeout.
+  ok = sem->Wait(0);
+  CHECK(!ok);
+  ok = sem->Wait(100);
+  CHECK(!ok);
+  ok = sem->Wait(1000);
+  CHECK(!ok);
+
+  // Semaphore signalled - no timeout.
+  sem->Signal();
+  ok = sem->Wait(0);
+  sem->Signal();
+  ok = sem->Wait(100);
+  sem->Signal();
+  ok = sem->Wait(1000);
+  CHECK(ok);
+}