merged streaming changes from libtorrent_aio into trunk

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9984 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
merge streaming fix from libtorrent_aio

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9987 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda