[boost] Potentially breaking change in VC8

Current builds of VC8 (newer than the June CTP) are implementing the change suggested by http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1757.html I don't know how or if this affects any Boost code, but it's something to watch out for. I would expect the next CTP of VC8 may well include this change. -cd PS: The change makes code like this ill-formed: template <unsigned n> struct bit_count { enum { value = n ? bit_count<n >> 1>::value+1 : 0 }; }; template <> struct bit_count<0> { enum { value = 0 }; };