hdf5_chunking_query_bmr

[svn-r10634] Purpose:
Use getenv_all for determining HDF5_PARAPREFIX instead of getenv

Description:
the environment variable HDF5_PARAPREFIX is now determined collectively, instead of
having each task call getenv.

Solution:
Environment variables set for task 0 often do not propogate to other tasks which
leads to obscure and hard to track down bugs.  getenv_all was written to overcome
this by having all tasks query a single task for the value of its environment.
Eventually, all calls to getenv will be migrated to use getenv_all.  For now,
only HDF5_PARAPREFIX will be determined this way.

Platforms tested:
heping pp, sol pp

Misc. update: