dirmngr: Allow to pass no filter args to dirmngr_ldap.

* dirmngr/dirmngr_ldap.c (main): Handle no args case.
--

This is required for example for CRLs.  The old code did not require
this because the hos was taken from the URL given has arg.

Signed-off-by: Werner Koch <wk@gnupg.org>
(cherry picked from commit f6e45671aa)

dirmngr/dirmngr_ldap.c

@@ -296,8 +296,6 @@ main (int argc, char **argv)
 
   if (log_get_errorcount (0))
     exit (2);
-  if (argc < 1)
-    gpgrt_usage (1);
 
   if (opt.alarm_timeout)
     {
@@ -318,11 +316,19 @@ main (int argc, char **argv)
 
   if (connect_ldap (&ld))
     any_err = 1;
+  else
+    {
+      if (!argc)
+        {
+          if (process_filter (ld, "(objectClass=*)"))
+            any_err = 1;
+        }
       else
         {
           for (; argc; argc--, argv++)
             if (process_filter (ld, *argv))
               any_err = 1;
+        }
       ldap_unbind (ld);
     }