fix(expressions): mend possible nil pointer deref edge case

If Anubis just started up, load averages may not be set in memory. This
can cause a nil pointer dereference which could fail requests with weird
errors until the async thread sets the load averages.

Ref: AWOO-005
Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/policy/expressions/loadavg.go

@@ -46,7 +46,7 @@ var (
 )
 
 func init() {
-	globalLoadAvg = &loadAvg{}
+	globalLoadAvg = &loadAvg{data: &load.AvgStat{}}
 	go globalLoadAvg.updateThread(context.Background())
 }