[boost] [UUID] seed_rng on Windows

Hi all, It would be nice if seed_rng used CryptGenRandom (or something similar) on Windows instead of trying to open /dev/urandom. The patch for seed_rng.hpp at: http://www.dynaroad.com/win.diff tries to use CryptGenRandom when BOOST_WINDOWS and _WINDOWS_ (i.e. windows.h has been included before uuid.hpp) are defined. This seems to work on Windows XP SP2 and Visual Studio 2005. Cheers, -kaj