Mark setting operating system limits from named.conf as ancient

After deprecating the operating system limits settings (coresize,
datasize, files and stacksize), mark them as ancient and remove the code
that sets the values from config.

fuzz/isc_lex_gettoken.in/named.conf

@@ -165,11 +165,7 @@ options {
 #maintain - ixfr - base no; // If yes, keep transaction log file for IXFR
 
 	max - ixfr - log - size 20m;
-	coresize 100;
-	datasize 101;
-	files 230;
 	max - cache - size 1m;
-	stacksize 231;
 	heartbeat - interval 1001;
 	interface - interval 1002;
 	statistics - interval 1003;