Move platform abstraction to base library

src/base/platform/semaphore.cc

 // Copyright 2013 the V8 project 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 "src/platform/semaphore.h"
+#include "src/base/platform/semaphore.h"
 
 #if V8_OS_MACOSX
 #include <mach/mach_init.h>
 #include <mach/task.h>
 #endif
 
 #include <errno.h>
 
-#include "src/checks.h"
-#include "src/platform/time.h"
+#include "src/base/logging.h"
+#include "src/base/platform/time.h"
 
 namespace v8 {
-namespace internal {
+namespace base {
 
 #if V8_OS_MACOSX
 
 Semaphore::Semaphore(int count) {
   kern_return_t result = semaphore_create(
       mach_task_self(), &native_handle_, SYNC_POLICY_FIFO, count);
   ASSERT_EQ(KERN_SUCCESS, result);
   USE(result);
 }
 
@@ skipping 152 matching lines @@
         return false;
       }
       ASSERT(result == WAIT_OBJECT_0);
       return true;
     }
   }
 }
 
 #endif  // V8_OS_MACOSX
 
-} }  // namespace v8::internal
+} }  // namespace v8::base