hdf5_der

[svn-r21411] 
Description:

 - Remove H5FD_mpiposix_flush function. I initially added it
   so the mpiposix driver had a place to coordinate the EOF
   value amongst all processes, but that was before we
   decided to introduce the H5FD_coordinate set of callbacks
   as a more appropriate place to do this. I just forgot to
   remove this function.

 - Add H5Fquery function for avoid_truncate and tie it to an
   associated H5F_AVOID_TRUNCATE() macro.

Tested:

- h5committested