port: split localtime_r definition and impl

src/windows/port.cc

@@ -55,6 +55,12 @@ int safe_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
   return _vsnprintf(str, size-1, format, ap);
 }
 
+#ifndef HAVE_LOCALTIME_R
+struct tm* localtime_r(const time_t* timep, struct tm* result) {
+  localtime_s(result, timep);
+  return result;
+}
+#endif // not HAVE_LOCALTIME_R
 #ifndef HAVE_SNPRINTF
 int snprintf(char *str, size_t size, const char *format, ...) {
   va_list ap;

src/windows/port.h

@@ -148,11 +148,8 @@ enum { PTHREAD_ONCE_INIT = 0 };   // important that this be 0! for SpinLock
 #endif // HAVE_PTHREAD
 
 #ifndef HAVE_LOCALTIME_R
-inline struct tm* localtime_r(const time_t* timep, struct tm* result) {
-  localtime_s(result, timep);
-  return result;
-}
-#endif
+extern struct tm* GOOGLE_GLOG_DLL_DECL localtime_r(const time_t* timep, struct tm* result);
+#endif // not HAVE_LOCALTIME_R
 
 inline char* strerror_r(int errnum, char* buf, size_t buflen) {
   strerror_s(buf, buflen, errnum);