Correct misplaced variable-delimiting brace in arc::cache.

manifests/cache.pp

@@ -54,7 +54,7 @@ class arc::cache
 
     cron {
 	'cache-clean':
-	    command => "/usr/libexec/arc/cache-clean -m90 -M95 -D INFO /export/cache >> ${arc}::logdir::logdir/cache-clean.log 2>&1",
+	    command => "/usr/libexec/arc/cache-clean -m90 -M95 -D INFO /export/cache >> ${arc::logdir::logdir}/cache-clean.log 2>&1",
 	    user    => 'root',
 	    month   => '*', monthday => '*', weekday => '*',
 	    hour    => '*', minute => '*/5';