dist_object can hang execution

[BrianS]

so noticed this when trying to make an rput_irregular example

    dist_object<uvector> dParticles(uvector(500));
    future<global_ptr<particle_t> > hiVectorF = rpc(nebrHi, [](dist_object<uvector>& d){
        return global_ptr<particle_t>(&((*d).front()));}, dParticles);
    std::cout<<"rpc called "<<me<<std::endl;
    hiVectorF.wait();
    std::cout<<"pointer arrived "<<me<<std::endl;

can produce output like this:

rpc called 5
rpc called 0
rpc called 2
rpc called 4
pointer arrived 4
rpc called 3
rpc called 7
rpc called 1
pointer arrived 0
pointer arrived 2
pointer arrived 5
rpc called 6
pointer arrived 1
pointer arrived 7
pointer arrived 6

In this case, rank 3 does not return from the wait call. The code hangs and the processes stay pegged at full CPU rate.

[Dan Bonachea]

Duplicate of #129.