hdf5

[svn-r17398] Description:
    First set of changes to move VFD 'truncate' call out of H5F_flush and defer
it until the file is closed.

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