Fix benchmark test problem on Windows

Author: yhirose

httplib.h

@@ -3283,8 +3283,14 @@ inline ssize_t select_write(socket_t sock, time_t sec, time_t usec) {
 
 inline Error wait_until_socket_is_ready(socket_t sock, time_t sec,
                                         time_t usec) {
+#if defined(__APPLE__) || defined(_WIN32)
+  // Use select() on macOS and Windows.
+  // WSAPoll() on Windows has known performance issues with localhost
+  // connections. See: https://daniel.haxx.se/blog/2012/10/10/wsapoll-is-broken/
 #ifdef __APPLE__
+  // On macOS, check if socket descriptor exceeds FD_SETSIZE
   if (sock >= FD_SETSIZE) { return Error::Connection; }
+#endif
 
   fd_set fdsr, fdsw;
   FD_ZERO(&fdsr);
@@ -3297,7 +3303,12 @@ inline Error wait_until_socket_is_ready(socket_t sock, time_t sec,
   tv.tv_usec = static_cast<decltype(tv.tv_usec)>(usec);
 
   auto ret = handle_EINTR([&]() {
+#ifdef _WIN32
+    // On Windows, the first parameter of select() is ignored
+    return select(0, &fdsr, &fdsw, nullptr, &tv);
+#else
     return select(static_cast<int>(sock + 1), &fdsr, &fdsw, nullptr, &tv);
+#endif
   });
 
   if (ret == 0) { return Error::ConnectionTimeout; }
@@ -3313,6 +3324,7 @@ inline Error wait_until_socket_is_ready(socket_t sock, time_t sec,
 
   return Error::Connection;
 #else
+  // Use poll() on Linux and other POSIX systems
   struct pollfd pfd_read;
   pfd_read.fd = sock;
   pfd_read.events = POLLIN | POLLOUT;