[libc][time] silence the incorrect type warning

components/libc/compilers/common/ctime.c

@@ -444,7 +444,7 @@ int settimeofday(const struct timeval *tv, const struct timezone *tz)
      * The tz_dsttime field has never been used under Linux.
      * Thus, the following is purely of historic interest.
      */
-    if (tv != RT_NULL && tv->tv_usec >= 0 && tv->tv_sec >= 0)
+    if (tv != RT_NULL && (long)tv->tv_usec >= 0 && (long)tv->tv_sec >= 0)
     {
         if (_control_rtc(RT_DEVICE_CTRL_RTC_SET_TIMEVAL, (void *)tv) == RT_EOK)
             return 0;