libtorc-audio: Fix potential crash in AudioDecoder
libtorc-audio: Ignore Torc generated errors returned from AVIOContext
libtorc-audio: Increase demuxer close timeout.

- was much too short for more complex buffer types that have significant
cleanup of their own.
libtorc-core: Add TorcBuffer::IgnoreEOF
libtorc-audio: Fix another potential segfault in AudioDecoder