error properly when lbcd fails to connect in HTTP POST mode

in the case where you're e.g. trying to connect to an
invalid address, the err vars in handleSendPostMessage()
were being shadowed inside the for loop. if c.httpClient.Do()
returned an error, that error never got returned upstream.
then ioutil.ReadAll(httpResponse.Body) would get a nil pointer
dereference. this fixes that case.

rpcclient/infrastructure.go

@@ -774,7 +774,8 @@ func (c *Client) handleSendPostMessage(jReq *jsonRequest) {
 	tries := 10
 	for i := 0; tries == 0 || i < tries; i++ {
 		bodyReader := bytes.NewReader(jReq.marshalledJSON)
-		httpReq, err := http.NewRequest("POST", url, bodyReader)
+		var httpReq *http.Request
+		httpReq, err = http.NewRequest("POST", url, bodyReader)
 		if err != nil {
 			jReq.responseChan <- &Response{result: nil, err: err}
 			return
@@ -786,7 +787,8 @@ func (c *Client) handleSendPostMessage(jReq *jsonRequest) {
 		}
 
 		// Configure basic access authorization.
-		user, pass, err := c.config.getAuth()
+		var user, pass string
+		user, pass, err = c.config.getAuth()
 		if err != nil {
 			jReq.responseChan <- &Response{result: nil, err: err}
 			return