check if abuf has been allocated. it can only be allocated once

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1965 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
add out-of-boundary access check

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1966 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
add out-of-boundary access check

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1967 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
fix out-of-index array access for when running more than 4 processes

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1968 c368ceb8-fd28-0410-a457-e46ee1d7cd4a