dirmngr: Always print a warning for a missing /etc/hosts.

* dirmngr/dns-stuff.c (libdns_init): No Windows specific handling of a
missing /etc/hosts.

My last comment on this was flawed. Windows seems to always have its
version of /etc/hosts. Only the en passant fixed bad escaping led me
assume that this was the case. Thanks to Andre for complaining about
my comment remark.

• Signed-off-by: Werner Koch <wk@gnupg.org>