[boost] [pool] Patches for #284 and #991 added

Hi, I put up two minimal of patches for the pool library. I couldn't figure out how to build the tests (if at all possible for this lib without making my own build setup.). I've at least tested the mem-leak patch (http://svn.boost.org/trac/boost/ticket/284) with our app and vc 7.1 and it works there. :) Cheers, /Marcus