New attempt at fixing the function pointer hash on the Sun compilers.
I think I was barking up the wrong tree - it could be that when calling
hash_value with a function pointer the compiler was choosing the
hash_value(bool) overload over the hash_value(T*) overload, so instead I'm
trying to call the correct one by giving it a template parameter. Another
alternative would be to calculate the hash function inside boost::hash.
Unfortunately, if I'm right, this means that other calls to hash_value will go
wrong for function pointers.
[SVN r39972]
Daniel James