feature(redhat): set NAMEDCONF file in sysconfig

Add the possibility to set named config file into sysconfig default file

Author: rgroux

bind/files/redhat/default

@@ -6,4 +6,8 @@
 # ROOTDIR="/var/named/chroot"
 # KEYTAB_FILE="/dir/file"
 # DISABLE_ZONE_CHECKING
+{% set sysconfigfile = salt['pillar.get']('bind:lookup:config', False) -%}
+{% if sysconfigfile -%}
+NAMEDCONF={{ sysconfigfile }}
+{% endif -%}
 OPTIONS="{{ param|join(' ') }}"