this check is complained by Cray compiler

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1886 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
check whether nonblocking requests' fileviews are contiguous and can be merged, to avoid creating a derived data type if possible

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1887 c368ceb8-fd28-0410-a457-e46ee1d7cd4a