Silent progress bar logs

[ring-c]

If there is no sd_log_cb set (no logs), there was a progress logs still present. This PR fixes that, no logs mean no logs. Progress bar logs set to own level so this type of logs can be filtered.

In log_printf() we are preparing logs in log_buffer, so we can send it to sd_log_cb. Should we exit early if there is no sd_log_cb set?