resolv: NI_IDN unimplemented
Some programs trying to use NI_IDN flag in case of it defined in netdb.h,
so hide it to suppress bad values for ai_flags.
Inspired by OpenWRT issue #12323
Signed-off-by: Leonid Lisovskiy <lly.dev@gmail.com>
Signed-off-by: Waldemar Brodkorb <wbx@uclibc-ng.org>