Fix timezone-dependant interpretation of database timestamp

The timestamp that is retrieved from DNS is in UTC and we must
not interpret as local time.
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

src/resolv.c

@@ -32,7 +32,7 @@ static int parse_timestamp(const unsigned char* txt, time_t* t) {
 
     // If the whole string has been parsed, we convert the parse value to time_t
     if (p && !*p) {
-        *t = mktime(&ts);
+        *t = timegm(&ts);
 
     // Otherwise we reset t
     } else {