unwrapped doesn't work with movable only types.

[sithhell]

unwrapped currently fails to compile for futures containing a movable only type due to the use of boost::fusion::fold. For example:

#include <hpx/hpx.hpp>
#include <hpx/lcos/future.hpp>
#include <hpx/util/unwrapped.hpp>

#include <utility>

struct movable_only
{
    movable_only() {}

    movable_only(movable_only const&) = delete;
    movable_only& operator= (movable_only const&) = delete;
};

int main()
{
    hpx::future<movable_only> f = hpx::make_ready_future(movable_only());
    hpx::util::unwrapped([](movable_only) {})(std::move(f));
}