DoS vector using incorrect TLS teardown

When in a TLS SOURCE connection the socket is closed without TLS teardown Icecast will read from the socket in a tight endless loop. This locks up the corresponding thread.

Affected at least: Icecast 2.4.4, Icecast 2.5 beta 2. May be related to OpenSSL version. Tested with version 1.0.1t.