feat use baidu.com for test

tile/net/http/http_client_test.cc

@@ -24,7 +24,7 @@ Get(const std::string &url, std::chrono::nanoseconds timeout = 20 * one_s) {
 bool IsWanAccessible() {
   static const auto kResult = /*!!Get("http://baidu.com") &&
                               !!Get("http://qq.com") &&*/
-      !!Get("http://example.com");
+      !!Get("http://www.baidu.com");
   return kResult;
 }
 
@@ -43,7 +43,7 @@ TEST(HttpClient, TestDomain) {
     TILE_LOG_INFO("WAN is not accessible, skip this test");
     return;
   }
-  auto resp = Get("http://example.com");
+  auto resp = Get("http://www.baidu.com");
   ASSERT_TRUE(resp);
   EXPECT_EQ(HttpStatus(200), resp->status());
 }
@@ -53,7 +53,7 @@ TEST(HttpClient, TestNotFound) {
     TILE_LOG_INFO("WAN is not accessible, skip this test");
     return;
   }
-  auto resp = Get("http://example.com/404");
+  auto resp = Get("http://www.baidu.com/404");
   ASSERT_TRUE(resp);
   EXPECT_EQ(HttpStatus(404), resp->status());
 }