hdf5

[svn-r17403] Description:
    Eliminate 'closing' flag to dataset flush routine, since all cached
dataset information has already been flushed when a file is closed and the
datasets themselves will be closed (and the dataset caches destroyed).

    Skip calling more flush routines when the file is closing, in preparation
for eventual separation of the 'flush' concept from the 'shutdown the cache'
concept.

Tested on:
    FreeBSD/32 6.3 (duty) in debug mode
    FreeBSD/64 6.3 (liberty) w/C++ & FORTRAN, in debug mode
    Linux/32 2.6 (kagiso) w/PGI compilers, w/C++ & FORTRAN, w/threadsafe,
        in debug mode
    Linux/64-amd64 2.6 (smirom) w/Intel compilers w/default API=1.6.x,
        w/C++ & FORTRAN, in production mode
    Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
        w/szip filter, in production mode
    Linux/64-ia64 2.6 (cobalt) w/Intel compilers, w/C++ & FORTRAN,
        in production mode
    Linux/64-ia64 2.4 (tg-login3) w/parallel, w/FORTRAN, in production mode
    Linux/64-amd64 2.6 (abe) w/parallel, w/FORTRAN, in production mode
    Mac OS X/32 10.5.8 (amazon) in debug mode
    Mac OS X/32 10.5.8 (amazon) w/C++ & FORTRAN, w/threadsafe,
        in production mode