build Use readlink() for NetBSD
build Use readlink() for NetBSD

NetBSD does not have HAVE_REALPATH, we need to use readlink() instead.

Signed-off-by: Donatas Abraitis <0c2d0dac0b941f1a5afedea3ce3f1f22fd14300a@opensourcerouting.org>

CESNET/libyang,CESNET/libyang