fix available() function on ssl_stream

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code@10376 a83610d8-ad2a-0410-a6ab-fc0612d85776
remove unused partial DHT lookups

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code@10377 a83610d8-ad2a-0410-a6ab-fc0612d85776