improve robustness of test_privacy and error messages of test_fast_extension

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@10170 a83610d8-ad2a-0410-a6ab-fc0612d85776
deprecate parts of cache_status and move those counters to session_stats counters. make the performance counters thread safe. fix some issues recently introduced to performance counters and the usage of them in client_test

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@10171 a83610d8-ad2a-0410-a6ab-fc0612d85776
switch over to use boost.atomic instead of home-built one

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@10172 a83610d8-ad2a-0410-a6ab-fc0612d85776