minor streaming improvements

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9992 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
fix windows build

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9993 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda