route: add manhole for pprof reasons

manhole.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"log"
+	"net"
+	"net/http"
+	_ "net/http/pprof"
+	"net/rpc"
+)
+
+func init() {
+	l, err := net.Listen("tcp", "127.0.0.2:0")
+	if err != nil {
+		log.Printf("manhole: cannot bind to 127.0.0.2:0: %v", err)
+		return
+	}
+
+	log.Printf("manhole: Now listening on http://%s", l.Addr())
+
+	rpc.HandleHTTP()
+	go http.Serve(l, nil)
+}