Increase rndc -dnssec status output size

BUFSIZ (on Windows 512) is not enough to output the status of
a DNSSEC policy and three DNSSEC keys.

Increase to hardcoded 4096, should be enough for most scenarios.

bin/named/server.c

@@ -14475,7 +14475,7 @@ named_server_dnssec(named_server_t *server, isc_lex_t *lex,
 	dns_dnsseckey_t *key;
 	const char *ptr;
 	/* variables for -status */
-	char output[BUFSIZ];
+	char output[4096];
 	isc_stdtime_t now;
 	isc_time_t timenow;
 	const char *dir;