Replace math.h with cmath

src/platform-openbsd.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 107 matching lines @@
 
 
 void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) {
   __asm__ __volatile__("" : : : "memory");
   // An x86 store acts as a release barrier.
   *ptr = value;
 }
 
 
 const char* OS::LocalTimezone(double time) {
-  if (isnan(time)) return "";
+  if (std::isnan(time)) return "";
   time_t tv = static_cast<time_t>(floor(time/msPerSecond));
   struct tm* t = localtime(&tv);
   if (NULL == t) return "";
   return t->tm_zone;
 }
 
 
 double OS::LocalTimeOffset() {
   time_t tv = time(NULL);
   struct tm* t = localtime(&tv);
@@ skipping 596 matching lines @@
   limit_mutex = CreateMutex();
 }
 
 
 void OS::TearDown() {
   delete limit_mutex;
 }
 
 
 } }  // namespace v8::internal