Explicit sorting across priority levels

There was a bug in the handling of prioritized host lists that caused
only the lowest priority level to be eligible for tophost.  This commit
amends the sorting and handling of the weighted lists so that it returns
the correct host.

dnssrv.tcl

@@ -54,9 +54,7 @@ namespace eval ::dnssrv {
 		return
 	}
 
-	proc apply_weightings {hostlist {_retlist retlist}} {
-		upvar 1 $_retlist retlist
-
+	proc weighted_list {hostlist} {
 		# This behavior is defined by RFC2782
 
 		set zero_weighted [list]
@@ -110,7 +108,7 @@ namespace eval ::dnssrv {
 			}
 		}
 
-		return
+		return $retlist
 	}
 
 	proc randomize_list {list} {
@@ -145,8 +143,8 @@ namespace eval ::dnssrv {
 			lappend pri($rdata(priority)) [list $rdata(weight) $target]
 		}
 
-		foreach priority [array names pri] {
-			apply_weightings $pri($priority) retlist
+		foreach priority [lsort -increasing -integer [array names pri]] {
+			set retlist [concat $retlist [weighted_list $pri($priority)]]
 		}
 
 		return $retlist