Disable transitional IDN rules, accept only sane names

Transitional encoding accepts every emoticon you can think about.
Because setlocale were not enabled before, IDN 2003 input was not
accepted by dnsmasq. It makes no sense therefore to maintain backward
compatibility. Accept only proper encoded unicode names and reject
random unicode characters.

Signed-off-by: Petr Menšík <pemensik@redhat.com>

src/util.c

@@ -233,8 +233,6 @@ char *canonicalise(char *in, int *nomem)
     {
 #  ifdef HAVE_LIBIDN2
       rc = idn2_to_ascii_lz(in, &ret, IDN2_NONTRANSITIONAL);
-      if (rc == IDN2_DISALLOWED)
-	rc = idn2_to_ascii_lz(in, &ret, IDN2_TRANSITIONAL);
 #  else
       rc = idna_to_ascii_lz(in, &ret, 0);
 #  endif