[master] DDoS mitigation features

3938.	[func]		Added quotas to be used in recursive resolvers
			that are under high query load for names in zones
			whose authoritative servers are nonresponsive or
			are experiencing a denial of service attack.

			- "fetches-per-server" limits the number of
			  simultaneous queries that can be sent to any
			  single authoritative server.  The configured
			  value is a starting point; it is automatically
			  adjusted downward if the server is partially or
			  completely non-responsive. The algorithm used to
			  adjust the quota can be configured via the
			  "fetch-quota-params" option.
			- "fetches-per-zone" limits the number of
			  simultaneous queries that can be sent for names
			  within a single domain.  (Note: Unlike
			  "fetches-per-server", this value is not
			  self-tuning.)
			- New stats counters have been added to count
			  queries spilled due to these quotas.

			See the ARM for details of these options. [RT #37125]

lib/dns/log.c

@@ -15,8 +15,6 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: log.c,v 1.49 2011/10/13 22:48:24 tbox Exp $ */
-
 /*! \file */
 
 /* Principal Authors: DCL */
@@ -47,6 +45,7 @@ LIBDNS_EXTERNAL_DATA isc_logcategory_t dns_categories[] = {
 	{ "rpz",	0 },
 	{ "rate-limit",	0 },
 	{ "cname",	0 },
+	{ "spill",	0 },
 	{ NULL, 	0 }
 };