platform: fix build on SmartOS

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 11 matching lines @@
 #define V8_BASE_PLATFORM_PLATFORM_H_
 
 #include <stdarg.h>
 #include <string>
 #include <vector>
 
 #include "src/base/build_config.h"
 #include "src/base/platform/mutex.h"
 #include "src/base/platform/semaphore.h"
 
-#ifdef __sun
-# ifndef signbit
-namespace std {
-int signbit(double x);
-}
-# endif
-#endif
-
 #if V8_OS_QNX
 #include "src/base/qnx-math.h"
 #endif
 
 // Microsoft Visual C++ specific stuff.
 #if V8_LIBC_MSVCRT
 
 #include "src/base/win32-headers.h"
 #include "src/base/win32-math.h"
 
@@ skipping 457 matching lines @@
   char name_[kMaxThreadNameLength];
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 } }  // namespace v8::base
 
 #endif  // V8_BASE_PLATFORM_PLATFORM_H_