assert that the random number generator is initialized before used

git-svn-id: http://libtorrent.googlecode.com/svn@10122 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
back port assert that the random number generator is seeded before use

git-svn-id: http://libtorrent.googlecode.com/svn@10123 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda