open up listener on gokrazy

cmd/qrbill-api/api.go

@@ -66,8 +66,11 @@ func qrchFromRequest(r *http.Request) *qrbill.QRCH {
 	}
 }
 
+// Overridden in api_gokrazy.go
+var defaultListenAddress = "localhost:9933"
+
 func logic() error {
-	var listen = flag.String("listen", "localhost:9933", "[host]:port to listen on")
+	var listen = flag.String("listen", defaultListenAddress, "[host]:port to listen on")
 	flag.Parse()
 
 	mux := http.NewServeMux()

cmd/qrbill-api/api_gokrazy.go

@@ -0,0 +1,9 @@
+// +build gokrazy
+
+package main
+
+func init() {
+	// Open up listener from localhost to all IP addresses, assuming that
+	// running on gokrazy means running as an appliance.
+	defaultListenAddress = ":9933"
+}