SCP/SFTP: Fix sftp_statemachine busyloop when *block=true by sunriseL · Pull Request #18311 · curl/curl

sftp_download_stat, sftp_upload_init, sftp_quote_stat, sftp_readdir will translate LIBSSH2_ERROR_EAGAIN to CURLE_OK and set *block to TRUE, but outer loop do not check *block, result in busy loop