Replace OVERRIDE->override and FINAL->final since we now require C++11.

src/base/platform/semaphore.h

Index: src/base/platform/semaphore.h
diff --git a/src/base/platform/semaphore.h b/src/base/platform/semaphore.h
index cbf8df2b7da396062514a09e167b8f7231c01c01..fa131018b37ae94be489a7e76cfdb10bb6fac4ff 100644
--- a/src/base/platform/semaphore.h
+++ b/src/base/platform/semaphore.h
@@ -31,7 +31,7 @@ class TimeDelta;
 // count reaches zero,  threads waiting for the semaphore blocks until the
 // count becomes non-zero.
 
-class Semaphore FINAL {
+class Semaphore final {
  public:
   explicit Semaphore(int count);
   ~Semaphore();