Eagerly set a pointer to nil to help GC (#1232)

Author: mehrdada

transport/transport.go

@@ -105,6 +105,7 @@ func (b *recvBuffer) load() {
 if len(b.backlog) > 0 {
 select {
 case b.c <- b.backlog[0]:
+b.backlog[0] = nil
 b.backlog = b.backlog[1:]
 default:
 }