Add code for explicit selection of pooled A records.

To better cope with round robin pooled A records like keys.gnupg.net
we need to keep some information on unresponsive hosts etc.  What we
do now is to resolve the hostnames, remember them and select a random
one.  If a host is dead it will be marked and a different one
selected.  This is intended to solve the problem of long timeouts due
to unresponsive hosts.

The code is not yet finished but selection works.

common/sysutils.c

@@ -150,6 +150,17 @@ get_session_marker (size_t *rlen)
   return marker;
 }
 
+/* Return a random number in an unsigned int. */
+unsigned int
+get_uint_nonce (void)
+{
+  unsigned int value;
+
+  gcry_create_nonce (&value, sizeof value);
+  return value;
+}
+
+
 
 #if 0 /* not yet needed - Note that this will require inclusion of
          cmacros.am in Makefile.am */