Fix Windows build problem

Author: yhirose

httplib.h

@@ -2054,13 +2054,18 @@ inline uint64_t Response::get_header_value_u64(const std::string &key,
 
 inline void default_socket_options(socket_t sock) {
   int opt = 1;
+#ifdef _WIN32
+  setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
+             reinterpret_cast<const char *>(&opt), sizeof(opt));
+#else
 #ifdef SO_REUSEPORT
   setsockopt(sock, SOL_SOCKET, SO_REUSEPORT,
              reinterpret_cast<const void *>(&opt), sizeof(opt));
 #else
   setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
              reinterpret_cast<const void *>(&opt), sizeof(opt));
 #endif
+#endif
 }
 
 inline const char *status_message(int status) {