use MPI bcast instead of stupid p2p

HPL claims to assume MPI 1.1 and yet they implement their own idiotic
binary-tree collectives.  This is pointless and horrendous.
use MPI_Reduce instead of stupid p2p

HPL claims to assume MPI 1.1 and yet they implement their own idiotic
binary-tree collectives.  This is pointless and horrendous.

whitespace change in bcast
use MPI collectives properly
whitespace
the failure to use MPI properly in this code is criminal
change from ifndef to ifdef so stupidity is disabled when not explicitly enabled