mktime() does not "normalize" struct tm argument

[Petro Karashchenko]

Hello team,

Recently I've been reviewing "strftime()" implementation from
"libs/libc/time/lib_strftime.c" and found interesting lines:
           /* %s: The number of seconds since the Epoch, that is,
            * since 1970-01-01 00:00:00 UTC.
            * Hmmm... mktime argume is not 'const'.
            */

           case 's':
             {
               len = snprintf(dest, chleft, "%ju",
                              (uintmax_t)mktime((FAR struct tm *)tm));
             }
             break;

This led me to the "mktime()" implementation and I found out that the NuttX
version of "mktime()" does not "normalize" struct tm argument. Is that a
designed behavior or this is a bug?

Best regards,
Petro