104 add a new PnetCDF hint nc_header_collective which is not necessary,
because we can simply check ROMIO hint romio_no_indep_rw to serve the
same purpose. Thus, this PR removes PnetCDF hint nc_header_collective
added in #104.
In all previous PnetCDF's releases, file header is written/read by rank 0 only
using MPI independent APIs. This can nullify ROMIO hint romio_no_indep_rw
if set by the user. To warrant no independent read/write, this PR first checks hint
romio_no_indep_rw and if set to true, then all file header I/Os are done
using MPI collective I/O calls, where only rank 0 makes non-zero length requests
while all others zero length (in order to participate the collective calls).
104 add a new PnetCDF hint
nc_header_collectivewhich is not necessary,because we can simply check ROMIO hint
romio_no_indep_rwto serve the same purpose. Thus, this PR removes PnetCDF hintnc_header_collectiveadded in #104.In all previous PnetCDF's releases, file header is written/read by rank 0 only using MPI independent APIs. This can nullify ROMIO hint
romio_no_indep_rwif set by the user. To warrant no independent read/write, this PR first checks hintromio_no_indep_rwand if set totrue, then all file header I/Os are done using MPI collective I/O calls, where only rank 0 makes non-zero length requests while all others zero length (in order to participate the collective calls).