Function esp_idf_svc::sys::esp_http_client_get_content_length

pub unsafe extern "C" fn esp_http_client_get_content_length(
    client: *mut esp_http_client,
) -> i64

@brief Get http response content length (from header Content-Length) the valid value if this function invoke after esp_http_client_perform

@param[in] client The esp_http_client handle

@return - (-1) Chunked transfer - Content-Length value as bytes