dirmngr: Fix error return for ADNS.

* dirmngr/dns-stuff.c (resolve_name_adns): Use RET for return value.

--
There are cases where libadns returns an error without setting the
variable ERRNO.

GnuPG-bug-id: 2745
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

dirmngr/dns-stuff.c

@@ -278,7 +278,7 @@ resolve_name_adns (const char *name, unsigned short port,
   my_protect ();
   if (ret)
     {
-      err = gpg_error_from_syserror ();
+      err = ret;
       log_error ("DNS query failed: %s\n", gpg_strerror (err));
       goto leave;
     }