vchoi_fork

[svn-r12401] Purpose:
Some collective chunk IO macro names are confusing, change them to more meaningful
names.

Description:
H5Pset_dxpl_mpio_chunk_opt will set a flag so that the library can do one linked IO or mul
ti-chunk IO with collective in chunking storage directly. That is, the library won't do an
alyses to determine this.

The flags for the enum type we used before are:
H5FD_MPIO_OPT_ONE_IO
H5FD_MPIO_OPT_MULTI_IO

They are not good names because of the following two reasons:

1. It doesn't reflect chunking storage
2. OPT is kind of redundant and misleading,
Solution:
We change the names to
H5FD_MPIO_CHUNK_ONE_IO
H5FD_MPIO_CHUNK_MULTI_IO

Platforms tested:
Since only macro names are changed, no need to test with h5committest.
Misc. update: