tool_util.c: Use GetTickCount64 if it is available

src/tool_util.c

@@ -33,10 +33,19 @@ struct timeval tool_tvnow(void)
   ** GetTickCount() is available on _all_ Windows versions from W95 up
   ** to nowadays. Returns milliseconds elapsed since last system boot,
   ** increases monotonically and wraps once 49.7 days have elapsed.
+  **
+  ** GetTickCount64() is available on Windows version from Windows Vista
+  ** and Windows Server 2008 up to nowadays. The resolution of the
+  ** function is limited to the resolution of the system timer, which
+  ** is typically in the range of 10 milliseconds to 16 milliseconds.
   */
   struct timeval now;
+#if defined(_WIN32_WINNT) && (_WIN32_WINNT >= 0x0600)
+  ULONGLONG milliseconds = GetTickCount64();
+#else
   DWORD milliseconds = GetTickCount();
-  now.tv_sec = milliseconds / 1000;
+#endif
+  now.tv_sec = (long)(milliseconds / 1000);
   now.tv_usec = (milliseconds % 1000) * 1000;
   return now;
 }