Method locking_callback

external/cpp-httplib/httplib.h:7277–7286

        private:
            static void locking_callback(int mode, int type, const char* /*file*/,
                int /*line*/) {
                auto& lk = (*openSSL_locks_)[static_cast<size_t>(type)];
                if (mode & CRYPTO_LOCK) {
                    lk.lock();
                }
                else {
                    lk.unlock();
                }
            }
        };

#endif