Fix unused variable on win32 build

src/base/platform/platform.h

 // Copyright 2012 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.
 
 // This module contains the platform-specific code. This make the rest of the
 // code less dependent on operating system, compilers and runtime libraries.
 // This module does specifically not deal with differences between different
 // processor architecture.
 // The platform classes have the same definition for all platforms. The
 // implementation for a particular platform is put in platform_<os>.cc.
@@ skipping 38 matching lines @@
 
 INLINE(intptr_t InternalGetExistingThreadLocal(intptr_t index));
 
 inline intptr_t InternalGetExistingThreadLocal(intptr_t index) {
   const intptr_t kTibInlineTlsOffset = 0xE10;
   const intptr_t kTibExtraTlsOffset = 0xF94;
   const intptr_t kMaxInlineSlots = 64;
   const intptr_t kMaxSlots = kMaxInlineSlots + 1024;
   const intptr_t kPointerSize = sizeof(void*);
   DCHECK(0 <= index && index < kMaxSlots);
+  USE(kMaxSlots);
   if (index < kMaxInlineSlots) {
     return static_cast<intptr_t>(__readfsdword(kTibInlineTlsOffset +
                                                kPointerSize * index));
   }
   intptr_t extra = static_cast<intptr_t>(__readfsdword(kTibExtraTlsOffset));
   DCHECK(extra != 0);
   return *reinterpret_cast<intptr_t*>(extra +
                                       kPointerSize * (index - kMaxInlineSlots));
 }
 
@@ skipping 439 matching lines @@
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_PLATFORM_PLATFORM_H_