Fix http_request example

1) WEB_PATH should path relative to document root of web server.
2) HTTP request should contain "Host" header of format "host:port".
3) Port number in the example should be configurable.

examples/protocols/http_request/main/http_request_example_main.c

@@ -24,13 +24,13 @@
 
 /* Constants that aren't configurable in menuconfig */
 #define WEB_SERVER "example.com"
-#define WEB_PORT 80
-#define WEB_URL "http://example.com/"
+#define WEB_PORT "80"
+#define WEB_PATH "/"
 
 static const char *TAG = "example";
 
-static const char *REQUEST = "GET " WEB_URL " HTTP/1.0\r\n"
-    "Host: "WEB_SERVER"\r\n"
+static const char *REQUEST = "GET " WEB_PATH " HTTP/1.0\r\n"
+    "Host: "WEB_SERVER":"WEB_PORT"\r\n"
     "User-Agent: esp-idf/1.0 esp32\r\n"
     "\r\n";
 
@@ -46,7 +46,7 @@ static void http_get_task(void *pvParameters)
     char recv_buf[64];
 
     while(1) {
-        int err = getaddrinfo(WEB_SERVER, "80", &hints, &res);
+        int err = getaddrinfo(WEB_SERVER, WEB_PORT, &hints, &res);
 
         if(err != 0 || res == NULL) {
             ESP_LOGE(TAG, "DNS lookup failed err=%d res=%p", err, res);