Changed type of mpiReductionBuffer to pvwdata_t.  Also removed PV_USE_MPI guard around mpiReductionBuffer and keepKernelsSynchronized_flag.
Changed type of mpiReductionBuffer to pvwdata_t.  Also removed PV_USE_MPI guard around mpiReductionBuffer and keepKernelsSynchronized_flag.

git-svn-id: 602a26e73ae9f2a14e2bb95676f2e137fcc39919@8602 7c0444ca-5550-0410-9008-faecdbe78eb5

PetaVision/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV