[request] Also clear `do` and `size` (#4465)

Those 2 attriburtes were not cleared as part of `Clear()` call.
Signed-off-by: chantra <chantr4@gmail.com>

request/request.go

@@ -338,6 +338,8 @@ func (r *Request) Clear() {
 	r.port = ""
 	r.localPort = ""
 	r.family = 0
+	r.size = 0
+	r.do = false
 }
 
 // Match checks if the reply matches the qname and qtype from the request, it returns