Fix a race in initialization of timezone cache in platform-win32.

src/platform-macos.cc

Index: src/platform-macos.cc
diff --git a/src/platform-macos.cc b/src/platform-macos.cc
index 683a04d3815aaf7c0a0a309444153613d755b44d..25ba0da0872345ada2abccc3a8f583fa042d018d 100644
--- a/src/platform-macos.cc
+++ b/src/platform-macos.cc
@@ -182,7 +182,7 @@ void OS::SignalCodeMovingGC() {
 }
 
 
-const char* OS::LocalTimezone(double time) {
+const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
   if (std::isnan(time)) return "";
   time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
   struct tm* t = localtime(&tv);
@@ -191,7 +191,7 @@ const char* OS::LocalTimezone(double time) {
 }
 
 
-double OS::LocalTimeOffset() {
+double OS::LocalTimeOffset(TimezoneCache* cache) {
   time_t tv = time(NULL);
   struct tm* t = localtime(&tv);
   // tm_gmtoff includes any daylight savings offset, so subtract it.