dtls: Properly display all errors/warnings from ERR queue (!5) · Merge requests · GStreamer / gst-plugins-bad

Conversion of the patch from #677 (comment 66858) into a MR made up of several commits.

Additional changes:

Implement @nirbheek's suggestion from #677 (comment 66859) and raise the log level for errno != 0
Add an ERR_clear_error call as required by SSL_get_error
Replace an if-else-chain with a switch

Edited Nov 05, 2018 by Jan Alexander Steffens