Revert "Let SSEClient::stop() interrupt a blocked read"

This reverts commit 3744227de2.

Shutting down the socket does not wake a read waiting in WSAPoll on
Windows while the peer stays silent, so stop() still waited out the read
timeout there and the new tests failed. Faster stop() on the other
platforms also let SSEIntegrationTest.ManualStop return while its server
handler still read a local of the test body (stack-use-after-return).
The fix will come back built on a wait that works on every platform.

test/test.cc

@@ -25637,78 +25637,6 @@ TEST_F(SSEIntegrationTest, ManualStop) {
   EXPECT_FALSE(sse.is_connected());
 }
 
-// Sends one event, then nothing until stop is set
-static Server::Handler idle_event_stream(std::atomic<bool> &stop) {
-  return [&stop](const Request &, Response &res) {
-    res.set_chunked_content_provider(
-        "text/event-stream", [&stop](size_t offset, DataSink &sink) {
-          if (offset == 0) {
-            std::string event = "data: hello\n\n";
-            sink.write(event.data(), event.size());
-          }
-          while (!stop.load()) {
-            std::this_thread::sleep_for(std::chrono::milliseconds(10));
-          }
-          return false;
-        });
-  };
-}
-
-// Both stop() and the destructor end a read blocked on /idle-stream promptly
-static void check_stop_interrupts_blocked_read(Client &client) {
-  client.set_read_timeout(30, 0);
-
-  for (auto by_destructor : {false, true}) {
-    std::atomic<bool> received{false};
-    std::chrono::steady_clock::time_point start;
-    {
-      sse::SSEClient sse(client, "/idle-stream");
-      sse.on_message([&](const sse::SSEMessage &) { received.store(true); });
-      sse.start_async();
-
-      for (int i = 0; i < 500 && !received.load(); ++i) {
-        std::this_thread::sleep_for(std::chrono::milliseconds(10));
-      }
-      ASSERT_TRUE(received.load());
-      // Let the client block in the next read
-      std::this_thread::sleep_for(std::chrono::milliseconds(100));
-
-      start = std::chrono::steady_clock::now();
-      if (!by_destructor) { sse.stop(); }
-    }
-    EXPECT_LT(std::chrono::steady_clock::now() - start,
-              std::chrono::seconds(2));
-  }
-}
-
-TEST_F(SSEIntegrationTest, StopInterruptsBlockedRead) {
-  server_->Get("/idle-stream", idle_event_stream(stop_server_));
-
-  Client client("localhost", get_port());
-  check_stop_interrupts_blocked_read(client);
-}
-
-#ifdef CPPHTTPLIB_SSL_ENABLED
-TEST(SSEClientSSLTest, StopInterruptsBlockedRead) {
-  SSLServer svr(SERVER_CERT_FILE, SERVER_PRIVATE_KEY_FILE);
-  std::atomic<bool> done{false};
-  svr.Get("/idle-stream", idle_event_stream(done));
-
-  auto port = svr.bind_to_any_port(HOST);
-  std::thread t([&] { svr.listen_after_bind(); });
-  auto se = detail::scope_exit([&] {
-    done.store(true);
-    svr.stop();
-    t.join();
-  });
-  svr.wait_until_ready();
-
-  Client client("https://localhost:" + std::to_string(port));
-  client.enable_server_certificate_verification(false);
-  check_stop_interrupts_blocked_read(client);
-}
-#endif
-
 // Test: SSEClient with custom headers
 TEST_F(SSEIntegrationTest, CustomHeaders) {
   // Setup a server endpoint that checks for custom header